bugfix: actions .yml location

.github/workflows/main-stock-ubuntu.yml

@@ -0,0 +1,33 @@
+name: build on ubuntu base platform
+
+on:
+  push:
+    branches: [ "main" ]
+  pull_request:
+    branches: [ "main" ]
+
+env:
+  # Customize CMake build type here
+  BUILD_TYPE: Release
+
+jobs:
+  build:
+    # This build won't be entirely reproducible, given ubuntu changes on github runners may
+    # introduce regressions.
+    #
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: checkout source
+        uses: actions/checkout@v3
+
+      - name: bootstrap xo-cmake
+        run: |
+          PREFIX=${{github.workspace}//local
+          mkdir -p ${PREFIX}
+          echo "::group::xo-cmake configure"
+          cmake -B .build0 -S xo-cmake -DCMAKE_INSTALL_PREFIX=${PREFIX}
+          echo "::group::xo-cmake build"
+          cmake --build .build0
+          echo "::group::xo-cmake install"
+          cmake --install .build0