BLD: use tempita for hashtable
- [x] closes #13786 
- [x] tests added / passed
- [x] passes `git diff upstream/master | flake8 --diff`

## [Current coverage](https://codecov.io/gh/pydata/pandas/pull/13815?src=pr) is 85.23% (diff: 100%)

> Merging [#13815](https://codecov.io/gh/pydata/pandas/pull/13815?src=pr) into [master](https://codecov.io/gh/pydata/pandas/branch/master?src=pr) will not change coverage

``` diff
@@             master     #13815   diff @@
==========================================
  Files           140        140          
  Lines         50420      50420          
  Methods           0          0          
  Messages          0          0          
  Branches          0          0          
==========================================
  Hits          42975      42975          
  Misses         7445       7445          
  Partials          0          0          
```

> Powered by [Codecov](https://codecov.io?src=pr). Last update [cc216ad...912aff8](https://codecov.io/gh/pydata/pandas/compare/cc216ada82a2b06a52524da7b1559a7f5e31b1c1...912aff87f7d5c14e32c507696b1b73505d6d67d5?src=pr)
 be sure to add to the linter as well.
 @jreback OK. linting is enabled for all `src/*.pxi.in` by default.
- https://github.com/pydata/pandas/blob/master/ci/lint.sh#L35
 thanks @sinhrks I know you wanted to add other types (e.g. int32), so can make another issue for that, but this is great.
