One final leftover in diff_urls of PRInfo

[Felixoid]

Changelog category (leave one):

• Not for changelog (changelog entry is not required)

Changelog entry (a user-readable short description of the changes that goes to CHANGELOG.md):

The default branch is not always master, and this is the case for https://github.com/ClickHouse/clickhouse-docs/actions/runs/6589156162/job/17902978407. Here we use the proper default branch, and get rid of the last appearance of diff_url

[robot-ch-test-poll2]

This is an automated comment for commit 849e441 with description of existing statuses. It's updated for the latest CI running

⏳ Click here to open a full report in a separate page

Successful checks

Check name	Description	Status
Fast test	Normally this is the first check that is ran for a PR. It builds ClickHouse and runs most of stateless functional tests, omitting some. If it fails, further checks are not started until it is fixed. Look at the report to see which tests fail, then reproduce the failure locally as described here	✅ success
Mergeable Check	Checks if all other necessary checks are successful	✅ success
Push to Dockerhub	The check for building and pushing the CI related docker images to docker hub	✅ success
Style Check	Runs a set of checks to keep the code style clean. If some of tests failed, see the related log from the report	✅ success

Check name	Description	Status
CI running	A meta-check that indicates the running CI. Normally, it's in success or pending state. The failed status indicates some problems with the PR	⏳ pending

[Felixoid]

The main thing is already checked here and in ClickHouse/clickhouse-docs#1513, so I cancel the workflow

[maxknv]

LGTM, thanks!