PYTHON-1294: Upgrade importlib-metadata to a much newer version

Author: absurdfarce

.travis.yml

@@ -7,6 +7,7 @@ python:
   - "3.5"
   - "3.6"
   - "3.7"
+  - "3.8"
   - "pypy2.7-6.0"
   - "pypy3.5"
 
@@ -24,7 +25,7 @@ addons:
     - libev-dev
 
 install:
-  - pip install --upgrade setuptools
+  - pip install --upgrade setuptools importlib-metadata
   - pip install tox-travis
   - if [[ $TRAVIS_PYTHON_VERSION != pypy3.5 ]]; then pip install lz4; fi