Announcing Sionna v0.12.1

[SebastianCa]

We are happy to announce the Sionna v0.12.1 release:

Fixes

• Issue with CRCEncoder and int_mod_2 function for large input tensors
• (fix: calculation of step noise in SSFM #76) Issue related to step noise calculation in SSFM
• (fec: ldpc: _llr_max attribute overwritten in base LDPCBPDecoder class  #75) Issue related to llr_max of LDPC5GDecoder
• Issue in the tests for KBest
• Updates documentation and fixes typos

Misc

• Add support for TensorFlow 2.11
• Version adjustments in requirements