sphinx-tabs is not compatible with Sphinx 9

[xqt]

Describe the bug

CONTEXT
Running Sphinx 9 with sphinx-tabs extension several warnings occurs. In result the documentation is broken for the current master release but it should be created like in stable release

BUG
Here are some warning messages I ran into...

13:13:43 WARNING: /src/.tox/doc/lib/python3.13/site-packages/sphinx_tabs/tabs.py:191: RemovedInSphinx11Warning: 'sphinx.environment.BuildEnvironment.app' is deprecated. Check CHANGES for Sphinx API modifications.
13:13:43   if self.env.app.builder.name not in get_compatible_builders(self.env.app):
13:13:43 
13:13:43 WARNING: /src/.tox/doc/lib/python3.13/site-packages/sphinx_tabs/tabs.py:107: RemovedInSphinx11Warning: 'sphinx.environment.BuildEnvironment.app' is deprecated. Check CHANGES for Sphinx API modifications.
13:13:43   if self.env.app.builder.name in get_compatible_builders(self.env.app):
13:13:43

Reproduce the bug

.

List your environment

No response

[bsipocz]

PRs to improve sphinx 9+ compatibility, including addressing upcoming deprecations are more than welcome!

Currently I see a variety of issues in addition to the upcoming deprecations mentioned above:

Results (3.62s):
         3 failed
         8 passed
       172 warnings
         3 errors

[theredcmdcraft]

i got the following error when running sphinx-build:

Traceback
=========

      File "myproject/build/env/lib/python3.11/site-packages/sphinx_tabs/tabs.py", line 69, in visit
        attrs.pop("backrefs")
    KeyError: 'backrefs'

[theredcmdcraft]

A temp fix can be, downgrading sphinx back to version 8 with pipenv install "sphinx<9.0"