Fix CI: Cannot uninstall a distutils installed project (#766)

* Pin llvmlite

* Add comments

Author: mthrok

.circleci/unittest/linux/scripts/environment.yml

@@ -8,10 +8,11 @@ dependencies:
   - pytest-cov
   - codecov
   - librosa
+  - llvmlite==0.31  # See https://github.com/pytorch/audio/pull/766
   - pip
   - pip:
     - clang-format
     - kaldi-io
     - scipy
     - parameterized
-    - numba==0.48
+    - numba==0.48  # See https://github.com/librosa/librosa/issues/1160