build(deps): bump the actions group across 1 directory with 2 updates

Bumps the actions group with 2 updates in the / directory: [actions/cache](https://github.com/actions/cache) and [docker/setup-buildx-action](https://github.com/docker/setup-buildx-action).


Updates `actions/cache` from 4 to 6
- [Release notes](https://github.com/actions/cache/releases)
- [Changelog](https://github.com/actions/cache/blob/main/RELEASES.md)
- [Commits](actions/cache@v4...v6)

Updates `docker/setup-buildx-action` from 4.2.0 to 4.3.0
- [Release notes](https://github.com/docker/setup-buildx-action/releases)
- [Commits](docker/setup-buildx-action@v4.2.0...v4.3.0)

---
updated-dependencies:
- dependency-name: actions/cache
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: actions
- dependency-name: docker/setup-buildx-action
  dependency-version: 4.3.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: actions
...

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

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -122,7 +122,7 @@ jobs:
       # nobody can reproduce locally. A miss just means the build runs, as it does today.
       - name: Cache RMG-Py Cython build
         id: rmg-build-cache
-        uses: actions/cache@v4
+        uses: actions/cache@v6
         with:
           path: |
             RMG-Py/**/*.so

.github/workflows/docker_build.yml

@@ -51,7 +51,7 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v7
       - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@v4.2.0
+        uses: docker/setup-buildx-action@v4.3.0
       # Add steps for CI checks of the Dockerfile
       - name: Build Docker Image (No Push)
         uses: docker/build-push-action@v7.3.0
@@ -87,7 +87,7 @@ jobs:
           username: ${{ secrets.DOCKERHUB_USERNAME }}
           password: ${{ secrets.DOCKERHUB_TOKEN }}
       - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@v4.2.0
+        uses: docker/setup-buildx-action@v4.3.0
       - name: Build and push RMG-Py
         uses: docker/build-push-action@v7.3.0
         with: