ci(gha): Enable gha cache (mode=min) in docker/build-push-action

Related: #627 (comment)

Author: erikmd

.github/workflows/deploy-master.yml

@@ -40,6 +40,8 @@ jobs:
         with:
           pull: true
           push: true
+          cache-from: "type=gha"
+          cache-to: "type=gha,mode=min"
           tags: "ocamlsf/learn-ocaml:master"
           platforms: "linux/amd64,linux/arm64/v8"
           labels: |
@@ -84,6 +86,8 @@ jobs:
           pull: true
           # load: true # implied by "driver: docker"
           push: true
+          cache-from: "type=gha"
+          cache-to: "type=gha,mode=min"
           target: client
           tags: "ocamlsf/learn-ocaml-client:master"
           platforms: "linux/amd64,linux/arm64/v8"

.github/workflows/release.yml

@@ -124,6 +124,8 @@ jobs:
         with:
           pull: true
           push: true
+          cache-from: "type=gha"
+          cache-to: "type=gha,mode=min"
           tags: |
             ocamlsf/learn-ocaml:latest
             ocamlsf/learn-ocaml:${{ steps.tag.outputs.tag }}
@@ -174,6 +176,8 @@ jobs:
           pull: true
           # load: true # implied by "driver: docker"
           push: true
+          cache-from: "type=gha"
+          cache-to: "type=gha,mode=min"
           target: client
           tags: |
             ocamlsf/learn-ocaml-client:latest