fix: package version

[charles-cooper]

this is a hybrid approach. previously we used bumpversion to bump the
version and then appended the commithash to the --version output. as
of 0.3.1, we used setuptools-scm to append the commit hash. however,
setuptools-scm did not have a way to create multiple versions -- one for
our --version output, and one for PKG-INFO.

this commit uses setuptools-scm to automate the global (ex. v0.3.2)
version string calculation, while using an auxiliary file to keep track
of the commit hash for --version.

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[codecov-commenter]

Codecov Report

Merging #2816 (f4f7107) into master (3b6a411) will decrease coverage by 0.02%.
The diff coverage is 57.14%.

@@            Coverage Diff             @@
##           master    #2816      +/-   ##
==========================================
- Coverage   87.48%   87.46%   -0.03%     
==========================================
  Files          94       94              
  Lines        9997    10001       +4     
  Branches     2478     2432      -46     
==========================================
+ Hits         8746     8747       +1     
- Misses        784      785       +1     
- Partials      467      469       +2     

Impacted Files	Coverage Δ
vyper/cli/vyper_compile.py	68.14% <ø> (ø)
vyper/cli/vyper_ir.py	0.00% <ø> (ø)
vyper/cli/vyper_json.py	79.78% <ø> (ø)
vyper/cli/vyper_serve.py	0.00% <0.00%> (ø)
vyper/__init__.py	76.47% <66.66%> (-5.35%)	⬇️
vyper/ir/s_expressions.py	91.17% <0.00%> (-2.95%)	⬇️
vyper/codegen/abi_encoder.py	86.53% <0.00%> (-0.13%)	⬇️
vyper/codegen/core.py	84.52% <0.00%> (-0.04%)	⬇️

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[fubuloubu]

If there's not a way to do this with setuptools_scm (add __commit__ to version.py separately from __version__) then this approach makes sense

[charles-cooper]

If there's not a way to do this with setuptools_scm (add __commit__ to version.py separately from __version__) then this approach makes sense

there is not. see here https://github.com/pypa/setuptools_scm/blob/ca3855ba66fa4cb100f5039eea909932f815a4a4/src/setuptools_scm/__init__.py#L34-L43 -- there is no way to get anything besides the package version string into version.py.