Run CI on windows python 3.8

.github/workflows/ci.yml

@@ -115,7 +115,7 @@ jobs:
     strategy:
       matrix:
         os: [ windows-latest ]
-        python-version: [3.7]
+        python-version: [3.7, 3.8]
 
     steps:
     - uses: actions/checkout@v2
@@ -130,8 +130,7 @@ jobs:
       if: startsWith(runner.os, 'Windows')
       with:
         path: ~\AppData\Local\pip\Cache
-        key: ${{ runner.os }}-pip
-        restore-keys: ${{ runner.os }}-pip
+        key: ${{ matrix.os }}-${{ matrix.python-version }}-pip
 
     - name: Installation
       run: |

build_helpers/install_windows.ps1

@@ -3,7 +3,15 @@
 # Invoke-WebRequest -Uri "https://download.lfd.uci.edu/pythonlibs/xxxxxxx/TA_Lib-0.4.17-cp37-cp37m-win_amd64.whl" -OutFile "TA_Lib-0.4.17-cp37-cp37m-win_amd64.whl"
 
 python -m pip install --upgrade pip
-pip install build_helpers\TA_Lib-0.4.17-cp37-cp37m-win_amd64.whl
+
+$pyv = python -c "import sys; print(f'{sys.version_info.major}.{sys.version_info.minor}')"
+
+if ($pyv == '3.7') {
+    pip install build_helpers\TA_Lib-0.4.17-cp37-cp37m-win_amd64.whl
+}
+if ($pyv == '3.8') {
+    pip install build_helpers\TA_Lib-0.4.17-cp38-cp38-win_amd64.whl
+}
 
 pip install -r requirements-dev.txt
 pip install -e .