Drop Python 3.5 support

pytest no longer supports it, and our CI is broken because of it.

.github/workflows/main.yml

@@ -11,19 +11,15 @@ jobs:
       fail-fast: false
       matrix:
         tox_env:
-          - "py35-pytestlatest"
           - "py36-pytestlatest"
           - "py37-pytestlatest"
           - "py38-pytestlatest"
           - "py39-pytestlatest"
           - "py38-pytestmain"
           - "py38-psutil"
-          - "linting"
 
         os: [ubuntu-latest, windows-latest]
         include:
-          - tox_env: "py35-pytestlatest"
-            python: "3.5"
           - tox_env: "py36-pytestlatest"
             python: "3.6"
           - tox_env: "py37-pytestlatest"
@@ -36,8 +32,6 @@ jobs:
             python: "3.8"
           - tox_env: "py38-psutil"
             python: "3.8"
-          - tox_env: "linting"
-            python: "3.7"
 
     steps:
     - uses: actions/checkout@v1
@@ -53,31 +47,13 @@ jobs:
       run: |
         tox -e ${{ matrix.tox_env }}
 
-  linting:
-
-    runs-on: ubuntu-latest
-
-    steps:
-    - uses: actions/checkout@v1
-    - name: Set up Python
-      uses: actions/setup-python@v1
-      with:
-        python-version: "3.7"
-    - name: Install tox
-      run: |
-        python -m pip install --upgrade pip
-        pip install tox
-    - name: Linting
-      run: |
-        tox -e linting
-
   deploy:
 
     if: github.event_name == 'push' && startsWith(github.event.ref, 'refs/tags')
 
     runs-on: ubuntu-latest
 
-    needs: [build, linting]
+    needs: build
 
     steps:
     - uses: actions/checkout@v1