Bump cygwin/cygwin-install-action from 4 to 5 (#491)

Bumps [cygwin/cygwin-install-action](https://github.com/cygwin/cygwin-install-action) from 4 to 5.
- [Release notes](https://github.com/cygwin/cygwin-install-action/releases)
- [Commits](cygwin/cygwin-install-action@v4...v5)

---
updated-dependencies:
- dependency-name: cygwin/cygwin-install-action
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/ci.yaml

@@ -157,7 +157,7 @@ jobs:
 
       - name: Setup Cygwin
         if: "contains(matrix.shell, 'cygwin')"
-        uses: cygwin/cygwin-install-action@v4
+        uses: cygwin/cygwin-install-action@v5
         with:
           platform: x64
           packages: gnupg2