Remove the deprecated numpy dtypes "int" and "float"

[jaycedowell]

It looks like this has sorta kinda already been merged in but with numpy.int64 replacing numpy.int and numpy.float64 replacing numpy.float. I think those are the correct sizes for native Python int's and float's so maybe this PR isn't needed? I guess the advantage of this approach is that integer allows both int32 and int64, and floating worth with float32 and float64.

[jaycedowell]

@dentalfloss1 @league Any opinions on this PR which would allow lower precision values to be stored in a "standard header"? I'm currently leaning towards keeping the current behavior in master and not merging this one.

[dentalfloss1]

I agree.

[codecov[bot]]

Codecov Report

Patch and project coverage have no change.

Comparison is base (becbf48) 65.39% compared to head (778c666) 65.39%. Report is 2 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #217 +/- ## ======================================= Coverage 65.39% 65.39% ======================================= Files 67 67 Lines 5840 5840 ======================================= Hits 3819 3819 Misses 2021 2021 ``` | [Files Changed](https://app.codecov.io/gh/ledatelescope/bifrost/pull/217?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=LEDA+Collaboration) | Coverage Δ | | |---|---|---| | [python/bifrost/header\_standard.py](https://app.codecov.io/gh/ledatelescope/bifrost/pull/217?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=LEDA+Collaboration#diff-cHl0aG9uL2JpZnJvc3QvaGVhZGVyX3N0YW5kYXJkLnB5) | `100.00% <ø> (ø)` | |

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[jaycedowell]

Motion carries, closing.