Bump actions/upload-artifact from 5 to 6 (#8850)

Bumps [actions/upload-artifact](https://github.com/actions/upload-artifact) from 5 to 6.
- [Release notes](https://github.com/actions/upload-artifact/releases)
- [Commits](actions/upload-artifact@v5...v6)

---
updated-dependencies:
- dependency-name: actions/upload-artifact
  dependency-version: '6'
  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>

Author: dependabot[bot]

.github/workflows/ci-caches.yml

@@ -103,7 +103,7 @@ jobs:
 
       # Upload the downloaded files as artifacts to GitHub
       - name: Upload artifacts to GitHub
-        uses: actions/upload-artifact@v5
+        uses: actions/upload-artifact@v6
         with:
           name: gmt-cache
           path: ~/.gmt/static
@@ -124,7 +124,7 @@ jobs:
           COASTLINEDIR: ${{ env.COASTLINEDIR }}
 
       - name: Upload artifacts to GitHub
-        uses: actions/upload-artifact@v5
+        uses: actions/upload-artifact@v6
         with:
           name: coastline-cache
           path: ${{ env.COASTLINEDIR }}
@@ -141,7 +141,7 @@ jobs:
         run: bash ci/install-dependencies-windows.sh
 
       - name: Upload artifacts to GitHub
-        uses: actions/upload-artifact@v5
+        uses: actions/upload-artifact@v6
         with:
           name: vcpkg-cache
           # VCPKG_INSTALLATION_ROOT is C:\vcpkg

.github/workflows/tests.yml

@@ -170,7 +170,7 @@ jobs:
         if: runner.os == 'Windows'
 
       - name: Upload build directory if failed
-        uses: actions/upload-artifact@v5
+        uses: actions/upload-artifact@v6
         with:
           name: BuildDirectory-${{ runner.os }}
           path: build/