MAINT: Remove self.assertAlmostEqual from testing
Title is self-explanatory.

Partially addresses #15990.

# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/16183?src=pr&el=h1) Report
> Merging [#16183](https://codecov.io/gh/pandas-dev/pandas/pull/16183?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/d647045d6b25e9549bbccb4c725030b82858c58b?src=pr&el=desc) will **not change** coverage.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/16183/graphs/tree.svg?width=650&height=150&src=pr&token=eZ4WkYLtcO)](https://codecov.io/gh/pandas-dev/pandas/pull/16183?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master   #16183   +/-   ##
=======================================
  Coverage   90.86%   90.86%           
=======================================
  Files         162      162           
  Lines       50827    50827           
=======================================
  Hits        46184    46184           
  Misses       4643     4643
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `88.64% <ø> (ø)` | :arrow_up: |
| #single | `40.33% <ø> (ø)` | :arrow_up: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/16183?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/util/testing.py](https://codecov.io/gh/pandas-dev/pandas/pull/16183?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvdGVzdGluZy5weQ==) | `79.07% <ø> (ø)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/16183?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/16183?src=pr&el=footer). Last update [d647045...8b8af9b](https://codecov.io/gh/pandas-dev/pandas/pull/16183?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/16183?src=pr&el=h1) Report
> Merging [#16183](https://codecov.io/gh/pandas-dev/pandas/pull/16183?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/096e2158f0101ecc34223e63ef276acb51d9ccca?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/16183/graphs/tree.svg?width=650&height=150&src=pr&token=eZ4WkYLtcO)](https://codecov.io/gh/pandas-dev/pandas/pull/16183?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #16183      +/-   ##
==========================================
- Coverage   90.88%   90.86%   -0.03%     
==========================================
  Files         162      162              
  Lines       50827    50827              
==========================================
- Hits        46195    46184      -11     
- Misses       4632     4643      +11
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `88.64% <ø> (-0.03%)` | :arrow_down: |
| #single | `40.33% <ø> (ø)` | :arrow_up: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/16183?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/util/testing.py](https://codecov.io/gh/pandas-dev/pandas/pull/16183?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvdGVzdGluZy5weQ==) | `79.07% <ø> (ø)` | :arrow_up: |
| [pandas/plotting/\_converter.py](https://codecov.io/gh/pandas-dev/pandas/pull/16183?src=pr&el=tree#diff-cGFuZGFzL3Bsb3R0aW5nL19jb252ZXJ0ZXIucHk=) | `63.54% <0%> (-1.82%)` | :arrow_down: |
| [pandas/core/common.py](https://codecov.io/gh/pandas-dev/pandas/pull/16183?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvY29tbW9uLnB5) | `91.03% <0%> (+0.34%)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/16183?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/16183?src=pr&el=footer). Last update [096e215...0dd458e](https://codecov.io/gh/pandas-dev/pandas/pull/16183?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
