docs: fix error handling import statements in README

Corrected the import statements for exception classes to properly
import from geocodio.exceptions module instead of the main geocodio
module. This ensures the code examples work correctly.

Author: MiniCodeMonkey

.github/workflows/ci.yml

@@ -2,7 +2,9 @@ name: CI
 
 on:
   push:
-    branches: [main, chore/ci-setup]
+    branches: [main]
+  pull_request:
+    branches: [main]
   workflow_dispatch:
 
 jobs:

README.md

@@ -115,7 +115,8 @@ Error Handling
 --------------
 
 ```python
-from geocodio import GeocodioClient, AuthenticationError, InvalidRequestError
+from geocodio import GeocodioClient
+from geocodio.exceptions import AuthenticationError, InvalidRequestError
 
 try:
     client = GeocodioClient("INVALID_API_KEY")