Ignore Python language refactors (.git-blame-ignore-revs) (#19150)

Ignore Python language refactors (`.git-blame-ignore-revs`)

 - https://github.com/element-hq/synapse/pull/19046
 - https://github.com/element-hq/synapse/pull/19111

### Pull Request Checklist

<!-- Please read
https://element-hq.github.io/synapse/latest/development/contributing_guide.html
before submitting your pull request -->

* [x] Pull request is based on the develop branch
* [x] Pull request includes a [changelog
file](https://element-hq.github.io/synapse/latest/development/contributing_guide.html#changelog).
The entry should:
- Be a short description of your change which makes sense to users.
"Fixed a bug that prevented receiving messages from other servers."
instead of "Moved X method from `EventStore` to `EventWorkerStore`.".
  - Use markdown where necessary, mostly for `code blocks`.
  - End with either a period (.) or an exclamation mark (!).
  - Start with a capital letter.
- Feel free to credit yourself, by adding a sentence "Contributed by
@github_username." or "Contributed by [Your Name]." to the end of the
entry.
* [x] [Code
style](https://element-hq.github.io/synapse/latest/code_style.html) is
correct (run the
[linters](https://element-hq.github.io/synapse/latest/development/contributing_guide.html#run-the-linters))

.git-blame-ignore-revs

@@ -26,3 +26,8 @@ c4268e3da64f1abb5b31deaeb5769adb6510c0a7
 # Update black to 23.1.0 (https://github.com/matrix-org/synapse/pull/15103)
 9bb2eac71962970d02842bca441f4bcdbbf93a11
 
+# Use type hinting generics in standard collections (https://github.com/element-hq/synapse/pull/19046)
+fc244bb592aa481faf28214a2e2ce3bb4e95d990
+
+# Write union types as X | Y where possible (https://github.com/element-hq/synapse/pull/19111)
+fcac7e0282b074d4bd3414d1c9c181e9701875d9

changelog.d/19150.misc

@@ -0,0 +1 @@
+Ignore recent Python language refactors from git blame (`.git-blame-ignore-revs`).