Bump tensorflow from 2.11.1 to 2.12.1 in /doc

Bumps [tensorflow](https://github.com/tensorflow/tensorflow) from 2.11.1 to 2.12.1.
- [Release notes](https://github.com/tensorflow/tensorflow/releases)
- [Changelog](https://github.com/tensorflow/tensorflow/blob/master/RELEASE.md)
- [Commits](tensorflow/tensorflow@v2.11.1...v2.12.1)

---
updated-dependencies:
- dependency-name: tensorflow
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

doc/requirements.txt

@@ -22,7 +22,7 @@ sphinxcontrib-devhelp==1.0.2
 sphinxcontrib-qthelp==1.0.3
 sphinxcontrib-htmlhelp==2.0.1
 sphinxcontrib-serializinghtml==1.1.5
-tensorflow==2.11.1; platform_machine == "x86_64"
+tensorflow==2.12.1; platform_machine == "x86_64"
 tensorflow_macos==2.9.0; sys_platform == "darwin" and platform_machine == "arm64"
 tensornetwork==0.3
 toml