Fix chocolatey upload

[agateau-gg]

Context

Automatic publication of the .nupkg file for Chocolatey failed during latest release. This PR fixes this.

Publication failed because there was no .nupkg file to publish:

Run scripts/chocolatey/push packages/ggshield.*.nupkg
  scripts/chocolatey/push packages/ggshield.*.nupkg
  shell: C:\Program Files\Git\bin\bash.EXE --noprofile --norc -e -o pipefail {0}
  env:
    CHOCOLATEY_API_KEY: ***
Chocolatey v2.4.3
File specified is either not found or not a .nupkg file. 'packages/ggshield.*.nupkg'

This was caused by the previous job step not downloading anything:

Run actions/download-artifact@v4
  with:
    pattern: ggshield.*.nupkg
    path: packages
    merge-multiple: false
    repository: GitGuardian/ggshield
    run-id: 15270372213
Found 5 artifact(s)
Filtering artifacts by pattern 'ggshield.*.nupkg'
Total of 0 artifact(s) downloaded
Download artifact has finished successfully

What has been done

There were 2 problems:

1. the pattern in download-artifact must match the GitHub-generated artifact names, here os-packages-windows-2022.zip
2. we must set merge-multiple to true otherwise the generated tree looks like this:

   packages
     os-packages-windows-2022
       ggshield-*-x86_64-pc-windows-msvc.zip
       ggshield.*.nupkg
   

Validation

I made a similar test commit that added a fake publish job to the ci.yml workflow: the job passed.

PR check list

• As much as possible, the changes include tests (unit and/or functional)
• If the changes affect the end user (new feature, behavior change, bug fix) then the PR has a changelog entry (see doc/dev/getting-started.md). If the changes do not affect the end user, then the skip-changelog label has been added to the PR.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.90%. Comparing base (9a6a393) to head (812be62).
Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1103   +/-   ##
=======================================
  Coverage   91.90%   91.90%           
=======================================
  Files         144      144           
  Lines        6091     6091           
=======================================
  Hits         5598     5598           
  Misses        493      493           

Flag	Coverage Δ
unittests	91.90% <ø> (ø)

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