Revert Linux and Mac 3.9 definitions since release versions are not working on either

.travis.yml

@@ -62,9 +62,6 @@ aliases:
 jobs:
   fast_finish: true
   allow_failures:
-    - name: Python 3.9 on Windows
-    - name: Python 3.9 on Linux
-    - name: Python 3.9 on MacOS
     - python: nightly
 
   include:
@@ -110,10 +107,21 @@ jobs:
 
     # Python 3.9 Tests
     - name: Python 3.9 on Linux
-      python: 3.9
+      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: 3.9.0
     - <<: *test_windows