Fix anonymous type detection for newer Clang version

[BrunoMSantos]

Clang 13 introduces a change to the anonymous type names forcing us to
update the regex to support both versions.

[jnikula]

Thanks, and sorry for the delay! This is what I used to test the change:

diff --git a/docker/test/Dockerfile b/docker/test/Dockerfile
index fbd362deacc6..0bbdb6e1c5ca 100644
--- a/docker/test/Dockerfile
+++ b/docker/test/Dockerfile
@@ -1,8 +1,8 @@
-FROM debian:bullseye
+FROM debian:bookworm
 
 RUN apt-get update
 RUN apt-get install -y \
-       python3-clang \
+       python3-clang-13 \
        python3-pip
 RUN apt-get clean

At some point I think we'll have to define the version combinations of {Sphinx, Clang, Python} we want to test. But I guess for now we can still go ad hoc and fix issues as they arise.

[jnikula]

Oops, we both forgot to run the new make check target for flake8. I opted to push a fix directly: 6dae9be ("flake8: silence a E501 line too long with "noqa: E501"")