fix(python): fix and check all uninstalled imports in ci

.github/workflows/test-python.yaml

@@ -72,12 +72,20 @@ jobs:
 
       - name: Check import without optional dependencies
         run: |
-          pip uninstall pandas -y
-          python -c 'import polars'
-          pip uninstall numpy -y
-          python -c 'import polars'
-          pip uninstall pyarrow -y
-          python -c 'import polars'
+          declare -a deps=("pandas"
+          "pyarrow"
+          "fsspec"
+          "matplotlib"
+          "backports.zoneinfo"
+          "connectorx"
+          "xlsx2csv"
+          )
+          for d in "${deps[@]}"
+          do
+            echo "uninstall $i and check imports..."
+            pip uninstall "$d" -y
+            python -c 'import polars'
+          done
 
   windows:
     runs-on: windows-latest

py-polars/polars/import_check.py

@@ -31,7 +31,12 @@ def zoneinfo_mod() -> ModuleType:
 
 
 def pkg_is_available(name: str) -> bool:
-    return importlib.util.find_spec(name) is not None
+    try:
+        return importlib.util.find_spec(name) is not None
+    # in python 3.7 backports.zoneinfo fails
+    # likely due to the dot in the package name
+    except ModuleNotFoundError:
+        return False
 
 
 def lazy_isinstance(value: Any, module_bound: str, types: Callable[[], Any]) -> bool: