Rethinking_2 Chp 6,7,8,9 conversion to PyMC v4 (#206)

* Updates and Chp07 conversion

- added tqdm to environment
- re-executed Chp 06 (there was a residual error message in the logs from the old code)
- updating Chp 07

* running pre_commits

* updating readme

* adding Chp_08 Updates to this PR

* Update Chp_09.ipynb

* Updating README

Author: yahrMason

Rethinking_2/Chp_06.ipynb

@@ -45,7 +45,7 @@ from the root directory.
 
 ## PyMC v4 Updates
 
-Work is on-going to update these notebooks to be compatible with PyMC v4. Currently chapters 2 through 6 have been converted.
+Work is on-going to update these notebooks to be compatible with PyMC v4. Currently chapters 2 through 9 have been converted.
 
 If you wish to run these notebooks, please create the v4 environment by running:
 

Rethinking_2/Chp_07.ipynb

@@ -12,6 +12,7 @@ dependencies:
   - aeppl==0.0.31
   - aesara==2.6.6
   - theano-pymc==1.1.2
+  - tqdm
   - mkl
   - mkl-service
   - pip