remove numpy 1.19.5 req and upgrade ubuntu to 18.04

Signed-off-by: Samuel Hoffman <hoffman.sc@gmail.com>

.github/workflows/ci.yml

@@ -16,7 +16,7 @@ on:
 # A workflow run is made up of one or more jobs that can run sequentially or in parallel
 jobs:
   build-py:
-    runs-on: ubuntu-16.04
+    runs-on: ubuntu-18.04
 
     strategy:
       fail-fast: false
@@ -44,7 +44,6 @@ jobs:
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip setuptools wheel
-          pip install numpy==1.19.5
           pip install -e '.[all]'
           pip install flake8
           pip list