Get details on ARM Git for Windows on CI from Git itself

This replaces the more complicated `sigcheck` logic with runs of
`git version --build-options` before and after upgrading Git for
Windows in the ARM `test-fixtures-windows` job.

The reason this wasn't done before was to avoid running the old
version at all, to maximize the chance that Inno Setup would be
able to remove it. On Windows, it is often difficult or infeasible
to remove or replace a running executable or other open file,
without terminating the executable or closing the file.

However, this was not the best tradeoff. Running `git version` is
unlikely to leave a danling process running. What we really want is
to avoid using the old Git substantially, such as in
`actions/checkout`, and this still avoids that.

The other reason to upgrade Git before running `actions/checkout`
is to verify that the new version of Git for Windows is working by
having `actions/checkout` use it. This change also preserves that.

Passing `--build-options` is important here because we do want to
verify that both the version of Git for Windows being replaced, and
(especially) the upgrade, are ARM64 builds.

(The `windows-11-arm` image currently has x86-64 builds of some
preinstalled software. But it's not expected to have a non-native
build of Git for Windows. If it does, then there may be more steps
that should be taken besides attempting to upgrade it.)

Author: EliahKagan

.github/workflows/ci.yml

@@ -263,29 +263,20 @@ jobs:
     runs-on: ${{ matrix.os }}
 
     steps:
+      - name: Report version/build of Git in this runner image
+        run: git version --build-options
       - name: Upgrade Git for Windows to latest stable release
-        # TODO: Remove this step once `windows-11-arm` ships a new enough version of Git.
+        # TODO: Remove this and related steps once `windows-11-arm` ships a new enough Git version.
         # (The Windows 11 ARM runner still ships Git 2.48.*, so it remains affected by #1849.)
         if: matrix.os == 'windows-11-arm'
         env:
           GH_TOKEN: ${{ github.token }}
         run: |
-          # Software downloaded in this step will be placed, and run from, here.
-          $workingDir = '~/dl'
-          mkdir $workingDir | Out-Null
-          cd $workingDir
-
-          # We use Sysinternals Sigcheck to show information about the installed Git for Windows
-          # before and after upgrade. (We are not actually using it to check any signatures.)
-          curl -LO 'https://live.sysinternals.com/sigcheck64.exe'
-          Write-Output 'BEFORE upgrading Git for Windows:'
-          .\sigcheck64.exe -accepteula -nobanner 'C:\Program Files\Git\clangarm64\bin\git.exe'
-
-          # Configuration for which Git for Windows installer to download and how to run it. See
-          # https://jrsoftware.org/ishelp/index.php?topic=setupcmdline on the Inno Setup arguments.
+          $workingDir = '~/git-dl'
           $repo = 'git-for-windows/git'
           $pattern = 'Git-*-arm64.exe'
           $log = 'setup-log.txt'
+          # Inno Setup args reference: https://jrsoftware.org/ishelp/index.php?topic=setupcmdline
           $arguments = @(
             '/VERYSILENT',
             '/SUPPRESSMSGBOXES',
@@ -296,17 +287,16 @@ jobs:
             '/FORCECLOSEAPPLICATIONS'
           )
 
-          # Download the Git for Windows release from GitHub and run the Inno Setup installer.
+          mkdir $workingDir | Out-Null
+          cd $workingDir
           gh release download --repo $repo --pattern $pattern
           $installer = Get-Item $pattern
           Start-Process -FilePath $installer -ArgumentList $arguments -NoNewWindow -Wait
 
-          # Report the effect of the upgrade.
-          Write-Output 'Tail of the upgrade log:'
           Get-Content -Path $log -Tail 50
-          Write-Output 'AFTER upgrading Git for Windows:'
-          .\sigcheck64.exe -nobanner 'C:\Program Files\Git\clangarm64\bin\git.exe'
-          git version
+      - name: Report version/build of Git after upgrade
+        if: matrix.os == 'windows-11-arm'
+        run: git version --build-options
       - uses: actions/checkout@v4
       - name: Install rustup
         if: matrix.os == 'windows-11-arm'