Add enable corepack step to workflow.

Author: awaitlink

.github/workflows/web_app.yml

@@ -30,6 +30,8 @@ jobs:
             ~/.cargo/git/db/
             target/
           key: ${{ runner.os }}-${{ steps.toolchain.outputs.rustc_hash }}-cargo-${{ hashFiles('**/Cargo.lock') }}
+      - name: "Enable corepack"
+        run: corepack enable
       - name: "Yarn: install"
         run: yarn install
       - name: "Trunk: build"