ci: use standalone Corepack for Yarn (#107)

Author: MikeMcC399

.github/workflows/ci-build-all-pm.yml

@@ -77,9 +77,12 @@ jobs:
               uses: actions/setup-node@v4
               with:
                   node-version: "lts/*"
-            - name: yarn add
+            - name: Install Corepack latest
               run: |
+                  npm install -g corepack@latest
                   corepack enable yarn
+            - name: yarn add
+              run: |
                   corepack use yarn@latest
                   yarn init -p
                   yarn add ./eslint-css-${{ needs.npm-build.outputs.version }}.tgz -D