Bump docker/bake-action from 1 to 1.4.0

Bumps [docker/bake-action](https://github.com/docker/bake-action) from 1 to 1.4.0.
- [Release notes](https://github.com/docker/bake-action/releases)
- [Commits](https://github.com/docker/bake-action/compare/v1...v1.4.0)

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

.github/workflows/validate.yml

@@ -19,6 +19,6 @@ jobs:
         uses: actions/checkout@v2
       -
         name: Validate
-        uses: docker/bake-action@v1
+        uses: docker/bake-action@v1.4.0
         with:
           targets: validate