Allow EAGER_IMPORT="" to disable it

Co-authored-by: Chris Markiewicz <effigies@gmail.com>

Author: stefanv

src/lazy_loader/__init__.py

@@ -92,7 +92,7 @@ def __getattr__(name):
     def __dir__():
         return __all__.copy()
 
-    eager_import = os.environ.get("EAGER_IMPORT", "") != "0"
+    eager_import = os.environ.get("EAGER_IMPORT", "") not in ("0", "")
     if eager_import:
         for attr in set(attr_to_modules.keys()) | submodules:
             __getattr__(attr)