CHANGELOG and README updates for 0.9.12.1

CHANGELOG

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 # CHANGELOG
 
+## [0.9.12.1] - 2024-02-07
+
+### Added
+* Warnings for JupyterLab incompatibility (#328)
+* Warning for modifying static DataSets (#340)
+* Keyword argument to change ForwardSim types at Protocol runtime (#358)
+* Flag to drop new `delay` instructions in QASM2 circuit output (#377)
+* Warning for non-TP gauge transformations on CPTPLND-parameterized objects (#378)
+* Code owner assignments (#384)
+* A new AffineShiftOp modelmember (#386)
+
+### Fixed
+* Several tutorial updates and fixes (#247, #395)
+* LGST fitting with various model parameterizations (#366)
+* Deprecated convolve import in scipy 1.12 (#391, #392)
+
+### Changed
+* Stricter enforcement of line labels when using "*" in circuits (#373)
+* Reimplementation of ProtectedArray (#386)
+* GitHub runner updates for faster runs on development branches (#388)
+
 ## [0.9.12] - 2023-11-28
 
 ### Added

README.md

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 ********************************************************************************
-  pyGSTi 0.9
+  pyGSTi 0.9.12.1
 ********************************************************************************
 
 ![master build](https://github.com/pyGSTio/pyGSTi/workflows/Build%20and%20run%20tests/badge.svg?branch=master)