Simplify cibuildwheel before_all block for GNU/Linux

Author: molinav

.github/workflows/build.yml

@@ -53,10 +53,9 @@ jobs:
           - os: ubuntu-latest
             before_all: |
               echo "Starting BEFORE_ALL script"
+              echo "GEOS_DIR set to: ${GEOS_DIR}"
               cd "{package}"
-              export GEOS_DIR="$(pwd)/extern"
-              echo "GEOS_DIR set to: $GEOS_DIR"
-              python -c "import sys; sys.path.append('utils'); from GeosLibrary import GeosLibrary; GeosLibrary('3.6.5', root='extern').build('extern', njobs=16)"
+              python -c "import utils; utils.GeosLibrary('${GEOS_VERSION}').build('${GEOS_DIR}', njobs=2)"
             # LD_LIBRARY_PATH in environment is needed by auditwheel.
             environment: >-
               GEOS_DIR="/project/packages/basemap/extern"