ci: Setup Github Actions for Windows.

Author: ganpa3

.github/workflows/zulip-tests.yml

@@ -27,11 +27,15 @@ jobs:
           tools/lint --skip=gitlint
 
   test:
-    runs-on: ubuntu-latest
+    runs-on: ${{ matrix.os }}
     strategy:
       fail-fast: false
       matrix:
+        os: [ubuntu-latest, windows-latest]
         python-version: [3.6, 3.7, 3.8, 3.9]
+        exclude:
+          - os: windows-latest
+            python-version: 3.6 # cryptography install fails on Windows with python 3.6 since pip is quite old.
 
     steps:
       - uses: actions/checkout@v2
@@ -42,12 +46,19 @@ jobs:
           python-version: ${{ matrix.python-version }}
 
       - name: Install dependencies
-        run: tools/provision --force
+        run: python tools/provision --force
 
-      - name: Running Test-Suite
+      - if: runner.os == 'Linux'
+        name: Running Test-Suite on Linux
         run: |
           source zulip-api-py3-venv/bin/activate
           tools/test-main
 
+      - if: runner.os == 'Windows'
+        name: Running Test-Suite on Windows
+        run: |
+          zulip-api-py3-venv\Scripts\Activate.ps1
+          tools\test-main.ps1
+
       - name: Codecov
         uses: codecov/codecov-action@v1.2.1