ci: move validate to a dedicated workflow

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

.github/workflows/test.yml

@@ -10,25 +10,6 @@ on:
       - '.github/*-releases.json'
 
 jobs:
-  validate:
-    runs-on: ubuntu-latest
-    strategy:
-      fail-fast: false
-      matrix:
-        target:
-          - lint
-          - vendor-validate
-          - license-validate
-    steps:
-      -
-        name: Checkout
-        uses: actions/checkout@v3
-      -
-        name: Validate
-        uses: docker/bake-action@v2
-        with:
-          targets: ${{ matrix.target }}
-
   test:
     runs-on: ubuntu-latest
     steps:

.github/workflows/validate.yml

@@ -0,0 +1,43 @@
+name: validate
+
+on:
+  workflow_dispatch:
+  push:
+    branches:
+      - 'main'
+  pull_request:
+    paths-ignore:
+      - '.github/*-releases.json'
+
+jobs:
+  prepare:
+    runs-on: ubuntu-20.04
+    outputs:
+      targets: ${{ steps.targets.outputs.matrix }}
+    steps:
+      -
+        name: Checkout
+        uses: actions/checkout@v3
+      -
+        name: Matrix
+        id: targets
+        run: |
+          echo "matrix=$(docker buildx bake validate --print | jq -cr '.group.validate.targets')" >> $GITHUB_OUTPUT
+
+  validate:
+    runs-on: ubuntu-latest
+    needs:
+      - prepare
+    strategy:
+      fail-fast: false
+      matrix:
+        target: ${{ fromJson(needs.prepare.outputs.targets) }}
+    steps:
+      -
+        name: Checkout
+        uses: actions/checkout@v3
+      -
+        name: Validate
+        uses: docker/bake-action@v2
+        with:
+          targets: ${{ matrix.target }}