Add a pre-check job to bootstrap the environment on Python 3.6 (#36358)

* Add a pre-check job that just bootstrap the environment on Python 3.6
* py-typing-extension: restore information on Python 3.6 installation
* Fix job name, try to run quick test on installed python packages

.github/workflows/valid-style.yml

@@ -58,3 +58,28 @@ jobs:
     with:
       with_coverage: ${{ inputs.with_coverage }}
       python_version: '3.11'
+  # Check that spack can bootstrap the development environment on Python 3.6 - RHEL8
+  bootstrap-dev-rhel8:
+    runs-on: ubuntu-latest
+    container: registry.access.redhat.com/ubi8/ubi
+    steps:
+      - name: Install dependencies
+        run: |
+          dnf install -y \
+              bzip2 curl file gcc-c++ gcc gcc-gfortran git gnupg2 gzip \
+              make patch tcl unzip which xz
+      - uses: actions/checkout@24cb9080177205b6e8c946b17badbe402adc938f # @v2
+      - name: Setup repo and non-root user
+        run: |
+          git --version
+          git fetch --unshallow
+          . .github/workflows/setup_git.sh
+          useradd spack-test
+          chown -R spack-test .
+      - name: Bootstrap Spack development environment
+        shell: runuser -u spack-test -- bash {0}
+        run: |
+          source share/spack/setup-env.sh
+          spack -d bootstrap now --dev
+          spack style -t black
+          spack unit-test -V