Fix bug in validate-external-links.py script (#3516)

## Description

This fixes a bug in the script `validate-external-links.py`:

```
During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/runner/_work/infra-config/infra-config/website/scripts/validate-external-links.py", line 162, in <module>
    external_links += [check_link(link, internal_url) for link
  File "/home/runner/_work/infra-config/infra-config/website/scripts/validate-external-links.py", line 162, in <listcomp>
    external_links += [check_link(link, internal_url) for link
  File "/home/runner/_work/infra-config/infra-config/website/scripts/validate-external-links.py", line 121, in check_link
    return ExternalLink(True, page, url, -1, f'Request exception: {str(e)}')
NameError: name 'e' is not defined
```


https://github.com/WATonomous/infra-config/actions/runs/12543562204/job/34975031171?pr=3501

<img width="2032" alt="image"
src="https://github.com/user-attachments/assets/a2bd60dc-da71-4f59-8d59-4e234430536c"
/>


## Checklist
- [x] I have read and understood the [WATcloud
Guidelines](https://cloud.watonomous.ca/docs/community-docs/watcloud/guidelines)
- [x] I have performed a self-review of my code

scripts/validate-external-links.py

@@ -116,7 +116,7 @@ def check_link(url: str, page: str) -> ExternalLink:
 
     except requests.exceptions.Timeout:
         return ExternalLink(True, page, url, -1, "Timeout")
-    except requests.exceptions.RequestException:
+    except requests.exceptions.RequestException as e:
         # Any error like connection issues are treated as broken links
         return ExternalLink(True, page, url, -1, f'Request exception: {str(e)}')