docs: update version to v4

Signed-off-by: CrazyMax <crazy-max@users.noreply.github.com>

README.md

@@ -74,7 +74,7 @@ jobs:
           password: ${{ secrets.DOCKERHUB_TOKEN }}
       -
         name: Build and push
-        uses: docker/build-push-action@v3
+        uses: docker/build-push-action@v4
         with:
           push: true
           tags: user/app:latest
@@ -99,7 +99,7 @@ to the default Git context:
         uses: docker/setup-buildx-action@v2
       -
         name: Build and push
-        uses: docker/build-push-action@v3
+        uses: docker/build-push-action@v4
         with:
           context: "{{defaultContext}}:mysubdir"
           push: true
@@ -122,7 +122,7 @@ named `GIT_AUTH_TOKEN` to be able to authenticate against it with Buildx:
 ```yaml
       -
         name: Build and push
-        uses: docker/build-push-action@v3
+        uses: docker/build-push-action@v4
         with:
           push: true
           tags: user/app:latest
@@ -161,7 +161,7 @@ jobs:
           password: ${{ secrets.DOCKERHUB_TOKEN }}
       -
         name: Build and push
-        uses: docker/build-push-action@v3
+        uses: docker/build-push-action@v4
         with:
           context: .
           push: true

TROUBLESHOOTING.md

@@ -58,7 +58,7 @@ jobs:
         uses: crazy-max/ghaction-setup-containerd@v2
       -
         name: Build Docker image
-        uses: docker/build-push-action@v3
+        uses: docker/build-push-action@v4
         with:
           context: .
           platforms: linux/amd64,linux/arm64
@@ -111,7 +111,7 @@ to generate sanitized tags:
     tags: latest
 
 - name: Build and push
-  uses: docker/build-push-action@v3
+  uses: docker/build-push-action@v4
   with:
     context: .
     push: true
@@ -129,7 +129,7 @@ Or a dedicated step to sanitize the slug:
     script: return 'ghcr.io/${{ github.repository }}'.toLowerCase()
 
 - name: Build and push
-  uses: docker/build-push-action@v3
+  uses: docker/build-push-action@v4
   with:
     context: .
     push: true