Bump docker/build-push-action from 6.13.0 to 6.18.0 (#220)

Bumps [docker/build-push-action](https://github.com/docker/build-push-action) from 6.13.0 to 6.18.0.
- [Release notes](https://github.com/docker/build-push-action/releases)
- [Commits](docker/build-push-action@ca877d9...2634353)

---
updated-dependencies:
- dependency-name: docker/build-push-action
  dependency-version: 6.18.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Charles Sibbald <123247+casibbald@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/ci.yaml

@@ -87,7 +87,7 @@ jobs:
         run: git config --global url."https://${GITHUB_BUILD_USERNAME}:${GITHUB_BUILD_TOKEN}@github.com".insteadOf "https://github.com"
 
       - name: Build Docker image (test only)
-        uses: docker/build-push-action@ca877d9245402d1537745e0e356eab47c3520991 # v6.13.0
+        uses: docker/build-push-action@263435318d21b8e681c14492fe198d362a7d2c83 # v6.18.0
         with:
           context: .
           push: false
@@ -156,7 +156,7 @@ jobs:
         run: git config --global url."https://${GITHUB_BUILD_USERNAME}:${GITHUB_BUILD_TOKEN}@github.com".insteadOf "https://github.com"
 
       - name: Build and push release Docker image
-        uses: docker/build-push-action@ca877d9245402d1537745e0e356eab47c3520991 # v6.13.0
+        uses: docker/build-push-action@263435318d21b8e681c14492fe198d362a7d2c83 # v6.18.0
         with:
           context: .
           push: true