fix: add browser header for test case (#1889)

**Issue number:**

### PR Type

**What kind of change does this PR introduce?**
* [ ] Feature
* [ ] Bug Fix
* [x] Refactoring (no functional or API changes)
* [ ] Documentation Update
* [ ] Maintenance (dependency updates, CI, etc.)

## Summary

### Changes

Added a try except block for the unit test case `test_const.py` to
handle 403 Forbidden errors, which occur when Splunk documentation
blocks automated requests.
Now, while directly accessing the `url` if it throws an exception, the
test case will automatically retry the request by adding a User-Agent
header to mimic browser behaviour.

### User experience

No change in user experience.

## Checklist

If an item doesn't apply to your changes, leave it unchecked.

### Review

* [x] self-review - I have performed a self-review of this change
according to the [development
guidelines](https://splunk.github.io/addonfactory-ucc-generator/contributing/#development-guidelines)
* [ ] Changes are documented. The documentation is understandable,
examples work [(more
info)](https://splunk.github.io/addonfactory-ucc-generator/contributing/#documentation-guidelines)
* [x] PR title and description follows the [contributing
principles](https://splunk.github.io/addonfactory-ucc-generator/contributing/#pull-requests)
* [ ] meeting - I have scheduled a meeting or recorded a demo to explain
these changes (if there is a video, put a link below and in the ticket)

### Tests

See [the testing
doc](https://splunk.github.io/addonfactory-ucc-generator/contributing/#build-and-test).

* [x] Unit - tests have been added/modified to cover the changes
* [ ] Smoke - tests have been added/modified to cover the changes
* [ ] UI - tests have been added/modified to cover the changes
* [x] coverage - I have checked the code coverage of my changes [(see
more)](https://splunk.github.io/addonfactory-ucc-generator/contributing/#checking-the-code-coverage)

**Demo/meeting:**

*Reviewers are encouraged to request meetings or demos if any part of
the change is unclear*

Author: hetangmodi-crest

tests/unit/test_const.py

@@ -1,14 +1,29 @@
 import re
 import urllib.request
+import urllib.error
 
 from splunk_add_on_ucc_framework.const import SPLUNK_COMMANDS
 
 
 def test_command_list_up_to_date():
-    with urllib.request.urlopen(
-        "https://docs.splunk.com/Documentation/Splunk/latest/SearchReference"
-    ) as resp:
-        content = resp.read().decode()
+    url = "https://docs.splunk.com/Documentation/Splunk/latest/SearchReference"
+    try:
+        with urllib.request.urlopen(url) as resp:
+            content = resp.read().decode()
+    except urllib.error.HTTPError:
+        # passing an imitation of browser header to make this a request from web browser
+        headers = {
+            "User-Agent": (
+                "Mozilla/5.0 (Windows NT 10.0; Win64; x64) "
+                "AppleWebKit/537.36 (KHTML, like Gecko) "
+                "Chrome/115.0.0.0 Safari/537.36"
+            )
+        }
+
+        req = urllib.request.Request(url, headers=headers)
+
+        with urllib.request.urlopen(req) as resp:
+            content = resp.read().decode()
 
     match = re.search(r"Search\s+Commands.+?<ul.+?>(.+?)</ul>", content, re.S)
     if match: