Drop external cmake and bison due to clingo incompatibility

Author: alecbcs

.github/workflows/clingo.yml

@@ -44,7 +44,7 @@ jobs:
           ref: 734c5db2121b01c373eed6538e452f18887e9e44
       # See https://github.com/actions/setup-python/issues/960
       - name: Workaround for broken Python versions from setup-python
-        run: brew install gettext zlib bison
+        run: brew install gettext zlib
       - uses: actions/setup-python@v4
         with:
           python-version: ${{ matrix.python-version }}
@@ -56,7 +56,6 @@ jobs:
 
           rm -rf $(spack location -p podman)
 
-          spack external find --not-buildable cmake bison
           spack config add "config:install_tree:padded_length:256"
 
           spack python clingo/install_clingo.py