smoke_test: Set git username and email before committing

[Turbo87]

On GitHub Actions the smoke test currently fails with:

Author identity unknown
*** Please tell me who you are.
Run
  git config --global user.email "you@example.com"
  git config --global user.name "Your Name"
to set your account's default identity.
Omit --global to set the identity only in this repository.

This change adds the necessary git commands to our setup to hopefully make the git commit call succeed now.

Related:

• smoke_test: Run git commit to work around cargo bug #9405

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 24 lines in your changes missing coverage. Please review.

Project coverage is 89.06%. Comparing base (5bc5796) to head (70223cc).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
crates/crates_io_smoke_test/src/git.rs	0.00%	18 Missing ⚠️
crates/crates_io_smoke_test/src/main.rs	0.00%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #9406      +/-   ##
==========================================
- Coverage   89.14%   89.06%   -0.08%     
==========================================
  Files         285      285              
  Lines       28914    28938      +24     
==========================================
  Hits        25774    25774              
- Misses       3140     3164      +24     

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