Follow PEP 440 for beta version naming

Author: michaelosthege

RELEASE-NOTES.md

@@ -7,7 +7,7 @@ Instead update the vNext section until 4.0.0 is out.
 ⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠
 -->
 
-## PyMC vNext (4.0.0-beta1 → 4.0.0-beta2 → 4.0.0)
+## PyMC vNext (4.0.0b1 → 4.0.0b2 → 4.0.0)
 ⚠ The changes below are the delta between the upcoming releases `v3.11.5` →...→ `v4.0.0`.
 
 ### No-yet working features

pymc/__init__.py

@@ -13,7 +13,7 @@
 #   limitations under the License.
 
 # pylint: disable=wildcard-import
-__version__ = "4.0.0-beta1"
+__version__ = "4.0.0b1"
 
 import logging
 import multiprocessing as mp