Revert "(temporary) add pyyaml to unittest requirements (#5099)" (#5112)

This reverts commit 743fe1a.

Author: datumbox

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

@@ -9,8 +9,6 @@ dependencies:
   - libpng
   - jpeg
   - ca-certificates
-  # TODO: remove this after https://github.com/pytorch/pytorch/issues/69905 is resolved
-  - pyyaml
   - pip:
     - future
     - pillow >=5.3.0, !=8.3.*

.circleci/unittest/windows/scripts/environment.yml

@@ -9,8 +9,6 @@ dependencies:
   - libpng
   - jpeg
   - ca-certificates
-  # TODO: remove this after https://github.com/pytorch/pytorch/issues/69905 is resolved
-  - pyyaml
   - pip:
     - future
     - pillow >=5.3.0, !=8.3.*