docs: v2.12.0 changelog

Author: kozistr

docs/changelogs/v2.12.0.md

@@ -4,6 +4,8 @@
 
 * Support `bitsandbytes` optimizer. (#211)
     * now, you can install with `pip3 install pytorch-optimizer[bitsandbytes]`
+    * supports 8 bnb optimizers.
+        * `bnb_adagrad8bit`, `bnb_adam8bit`, `bnb_adamw8bit`, `bnb_lion8bit`, `bnb_lamb8bit`, `bnb_lars8bit`, `bnb_rmsprop8bit`, `bnb_sgd8bit`.
 
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