Bump johnwason/vcpkg-action from 5 to 6

Bumps [johnwason/vcpkg-action](https://github.com/johnwason/vcpkg-action) from 5 to 6.
- [Release notes](https://github.com/johnwason/vcpkg-action/releases)
- [Commits](johnwason/vcpkg-action@v5...v6)

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

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/test_latest.yml

@@ -42,7 +42,7 @@ jobs:
         with:
           fetch-depth: 0
       - name: Install GSL
-        uses: johnwason/vcpkg-action@v5
+        uses: johnwason/vcpkg-action@v6
         id: vcpkg
         with:
           pkgs: gsl
@@ -89,7 +89,7 @@ jobs:
         with:
           fetch-depth: 0
       - name: Install GSL
-        uses: johnwason/vcpkg-action@v5
+        uses: johnwason/vcpkg-action@v6
         id: vcpkg
         with:
           pkgs: gsl