ci: remove specific shell

Author: zimeg

.github/workflows/ci-build.yml

@@ -64,12 +64,10 @@ jobs:
         run: npm run lint
       - name: Run tests (Node 18/20)
         if: matrix.node-version != '22.x' && matrix.node-version != '24.x'
-        shell: bash
         # Node 18 lacks --test-reporter; Node 20 has coverage bugs. Use simpler script.
         run: npm run test:node18 --workspaces --if-present
       - name: Run tests (Node 22+)
         if: matrix.node-version == '22.x' || matrix.node-version == '24.x'
-        shell: bash
         run: npm test
       - name: Upload code coverage
         if: matrix.node-version == '24.x' && matrix.os == 'ubuntu-latest'