DOC: Remove vendored IPython.sphinext
# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/18193?src=pr&el=h1) Report
> Merging [#18193](https://codecov.io/gh/pandas-dev/pandas/pull/18193?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/17e0b13095b23ade8e64434e88300b849bfadf01?src=pr&el=desc) will **decrease** coverage by `0.04%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/18193/graphs/tree.svg?width=650&height=150&src=pr&token=eZ4WkYLtcO)](https://codecov.io/gh/pandas-dev/pandas/pull/18193?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #18193      +/-   ##
==========================================
- Coverage   91.42%   91.38%   -0.05%     
==========================================
  Files         163      163              
  Lines       50064    50064              
==========================================
- Hits        45772    45751      -21     
- Misses       4292     4313      +21
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `89.19% <ø> (-0.03%)` | :arrow_down: |
| #single | `40.36% <ø> (-0.06%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/18193?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/io/gbq.py](https://codecov.io/gh/pandas-dev/pandas/pull/18193?src=pr&el=tree#diff-cGFuZGFzL2lvL2dicS5weQ==) | `25% <0%> (-58.34%)` | :arrow_down: |
| [pandas/plotting/\_converter.py](https://codecov.io/gh/pandas-dev/pandas/pull/18193?src=pr&el=tree#diff-cGFuZGFzL3Bsb3R0aW5nL19jb252ZXJ0ZXIucHk=) | `63.38% <0%> (-1.82%)` | :arrow_down: |
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/18193?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97.8% <0%> (-0.1%)` | :arrow_down: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/18193?src=pr&el=continue).
> **Legend** - [Click here to learn more](https://docs.codecov.io/docs/codecov-delta)
> `Δ = absolute <relative> (impact)`, `ø = not affected`, `? = missing data`
> Powered by [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/18193?src=pr&el=footer). Last update [17e0b13...902b75f](https://codecov.io/gh/pandas-dev/pandas/pull/18193?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/18193?src=pr&el=h1) Report
> Merging [#18193](https://codecov.io/gh/pandas-dev/pandas/pull/18193?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/17e0b13095b23ade8e64434e88300b849bfadf01?src=pr&el=desc) will **decrease** coverage by `0.02%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/18193/graphs/tree.svg?height=150&token=eZ4WkYLtcO&width=650&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/18193?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #18193      +/-   ##
==========================================
- Coverage    91.4%   91.38%   -0.03%     
==========================================
  Files         163      163              
  Lines       50064    50064              
==========================================
- Hits        45763    45751      -12     
- Misses       4301     4313      +12
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `89.19% <ø> (-0.03%)` | :arrow_down: |
| #single | `40.36% <ø> (ø)` | :arrow_up: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/18193?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/plotting/\_converter.py](https://codecov.io/gh/pandas-dev/pandas/pull/18193?src=pr&el=tree#diff-cGFuZGFzL3Bsb3R0aW5nL19jb252ZXJ0ZXIucHk=) | `63.38% <0%> (-1.82%)` | :arrow_down: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/18193?src=pr&el=continue).
> **Legend** - [Click here to learn more](https://docs.codecov.io/docs/codecov-delta)
> `Δ = absolute <relative> (impact)`, `ø = not affected`, `? = missing data`
> Powered by [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/18193?src=pr&el=footer). Last update [17e0b13...902b75f](https://codecov.io/gh/pandas-dev/pandas/pull/18193?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 Renders the same AFAICT. Apparently the `@savefig` puts files in a different place now, but not a big deal.

Dependencies should all be fine. We already include IPython in our doc build, and the updates I made to contributing last week include IPython. Yes!