Install pytest in Test Main workflow to enable testing (#37)

Author: pavelacamposp

.github/workflows/test_main.yml

@@ -34,8 +34,10 @@ jobs:
             sleep 5; \
           done
 
-      - name: Upgrade pip
-        run: python -m pip install --upgrade pip
+      - name: Upgrade pip and install pytest
+        run: |
+          python -m pip install --upgrade pip
+          pip install pytest
 
       - name: Install project package in editable mode
         run: |
@@ -71,8 +73,10 @@ jobs:
             sleep 5; \
           done
 
-      - name: Upgrade pip
-        run: python -m pip install --upgrade pip
+      - name: Upgrade pip and install pytest
+        run: |
+          python -m pip install --upgrade pip
+          pip install pytest
 
       - name: Install project package in editable mode
         run: |