ignore DataFrame test if not GeoPandas, give up on Python 3.7 builds (#137)

Author: hobu

.github/workflows/build.yml

@@ -25,7 +25,7 @@ jobs:
       matrix:
         os: ['ubuntu-latest', 'macos-latest', 'windows-latest']
         python-version: ['3.9', '3.10', '3.11']
-
+        
     steps:
     - name: Check out python-pdal
       uses: actions/checkout@v2