fix: resolve undefined variable and add env validation in AckKubestronautsReceived.py

1. Renamed variable from 'pwd' to 'KUBESTRONAUT_RECEIVERS' to match its usage on line 29.

2. Added validation to check if the environment variable is set, providing a clear error message instead of a cryptic runtime error.

Signed-off-by: LALANI DEVARSHI <thelogical369@gmail.com>

Author: codeMaestro78

Kubestronaut/AckKubestronautsReceived.py

@@ -19,7 +19,12 @@
 
 load_dotenv()
 # Store credentials
-pwd = os.getenv('KUBESTRONAUT_RECEIVERS')
+KUBESTRONAUT_RECEIVERS = os.getenv('KUBESTRONAUT_RECEIVERS')
+if not KUBESTRONAUT_RECEIVERS:
+    raise RuntimeError(
+        "Environment variable 'KUBESTRONAUT_RECEIVERS' is not set. "
+        "Please set it to the Google Sheets key before running this script."
+    )
 
 
 # Let's open the GoogleSheet to write Kubestronaut info + coupons