ci(validate): use matrix subaction

Signed-off-by: CrazyMax <1951866+crazy-max@users.noreply.github.com>

.github/workflows/validate.yml

@@ -33,51 +33,20 @@ jobs:
   prepare:
     runs-on: ubuntu-24.04
     outputs:
-      includes: ${{ steps.matrix.outputs.includes }}
+      includes: ${{ steps.generate.outputs.matrix }}
     steps:
       -
         name: Checkout
         uses: actions/checkout@v5
       -
-        name: Matrix
-        id: matrix
-        uses: actions/github-script@v7
+        name: Generate matrix
+        id: generate
+        uses: docker/bake-action/subaction/matrix@v6
         with:
-          script: |
-            let def = {};
-            await core.group(`Parsing definition`, async () => {
-              const printEnv = Object.assign({}, process.env, {
-                GOLANGCI_LINT_MULTIPLATFORM: process.env.GITHUB_REPOSITORY === 'docker/buildx' ? '1' : ''
-              });
-              const resPrint = await exec.getExecOutput('docker', ['buildx', 'bake', 'validate', '--print'], {
-                ignoreReturnCode: true,
-                env: printEnv
-              });
-              if (resPrint.stderr.length > 0 && resPrint.exitCode != 0) {
-                throw new Error(res.stderr);
-              }
-              def = JSON.parse(resPrint.stdout.trim());
-            });
-            await core.group(`Generating matrix`, async () => {
-              const includes = [];
-              for (const targetName of Object.keys(def.target)) {
-                const target = def.target[targetName];
-                if (target.platforms && target.platforms.length > 0) {
-                  target.platforms.forEach(platform => {
-                    includes.push({
-                      target: targetName,
-                      platform: platform
-                    });
-                  });
-                } else {
-                  includes.push({
-                    target: targetName
-                  });
-                }
-              }
-              core.info(JSON.stringify(includes, null, 2));
-              core.setOutput('includes', JSON.stringify(includes));
-            });
+          target: validate
+          fields: platforms
+        env:
+          GOLANGCI_LINT_MULTIPLATFORM: ${{ github.repository == 'docker/buildx' && '1' || '' }}
 
   validate:
     runs-on: ubuntu-24.04
@@ -88,12 +57,6 @@ jobs:
       matrix:
         include: ${{ fromJson(needs.prepare.outputs.includes) }}
     steps:
-      -
-        name: Prepare
-        run: |
-          if [ "$GITHUB_REPOSITORY" = "docker/buildx" ]; then
-            echo "GOLANGCI_LINT_MULTIPLATFORM=1" >> $GITHUB_ENV
-          fi
       -
         name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v3
@@ -107,4 +70,4 @@ jobs:
         with:
           targets: ${{ matrix.target }}
           set: |
-            *.platform=${{ matrix.platform }}
+            *.platform=${{ matrix.platforms }}