added main as runnable

app.py

@@ -10,4 +10,8 @@ def main():
     to_date = input("Enter to date (YYYY-MM-DD): ")
     user_name = input("Enter user name: ")
     text_classifier = tc.TextClassifier(from_date=from_date, to_date=to_date, user_name=user_name, num_tweets=20)
-    text_classifier.run_main_pipeline()
+    text_classifier.run_main_pipeline()
+
+
+if __name__ == "__main__":
+    main()