Fix build issues

.github/workflows/build.yml

@@ -31,10 +31,10 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v1
-      - name: Set up Python 3.8
+      - name: Set up Python 3.9
         uses: actions/setup-python@v1
         with:
-          python-version: 3.8
+          python-version: 3.9
       - name: Install dependencies
         run: pip install pandas pytest
       - name: Install package

requirements.txt

@@ -1,3 +1,4 @@
+importlib-metadata==4.13.*
 numpy==1.21.*
 scipy==1.7.*
 pandas==1.3.*