Revert "Clean up unneeded TOML modifications and other scaffolding not needed for 3.9"

This reverts commit 13b4266ed1.

.travis.yml

@@ -35,7 +35,6 @@ aliases:
         - $HOME/.pyenv/versions
         - $HOME/Library/Caches/pypoetry
     before_install:
-      - brew upgrade pyenv
       - eval "$(pyenv init -)"
       - pyenv install -s $JRNL_PYTHON_VERSION
       - pyenv global $JRNL_PYTHON_VERSION
@@ -111,10 +110,21 @@ jobs:
 
     # Python 3.9 Dev Tests
     - name: Python 3.9 on Linux
+      before_install:
+        - pip install toml
+        - python .build/allow_all_python_version.py
       python: 3.9-dev
     - <<: *test_mac
       name: Python 3.9 on MacOS
-      python: 3.9
+      before_install:
+        - brew upgrade pyenv
+        - eval "$(pyenv init -)"
+        - pyenv install -s $JRNL_PYTHON_VERSION
+        - pyenv global $JRNL_PYTHON_VERSION
+        - pip install --upgrade pip
+        - pip --version
+        - pip install toml
+        - python .build/allow_all_python_version.py
       env:
         JRNL_PYTHON_VERSION: 3.9.0b5
     - <<: *test_windows