fix: pm.require from the REPL

The stack filename is `<stdin>` for the REPL, which is not a valid path

Author: Xmader

python/pythonmonkey/require.py

@@ -253,4 +253,7 @@ def createRequire(filename: str):
 def require(moduleIdentifier: str):
     # Retrieve the caller’s filename from the call stack
     filename = inspect.stack()[1].filename
+    # From the REPL, the filename is "<stdin>", which is not a valid path
+    if not os.path.exists(filename):
+      filename = os.path.join(os.getcwd(), "__main__") # use the CWD instead
     return createRequire(filename)(moduleIdentifier)