Revert Use cache for pip

This commit gets rid of using any type of cache (introduced in 135c95f)
This is to ensure having no surprises in future. This was discussed in
https://github.com/nexB/vulnerablecode/wiki/WeeklyMeetings#meeting-on-tuesday-2021-07-27-at-1300-utc

Signed-off-by: Hritik Vijay <hritikxx8@gmail.com>

Author: Hritik14

.github/workflows/main.yml

@@ -7,48 +7,28 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - name: Check out repository code
+      - name: Check code
         uses: actions/checkout@v2
 
-      - name: Set up Python 3.8
+      - name: Set up Python 3.8.11
         uses: actions/setup-python@v2
         with:
-          python-version: 3.8
-
-      - name: Restore cache
-        uses: actions/cache@v2
-        with:
-          path: venv
-          key: ${{ runner.os }}-venv-${{ hashFiles('**/requirements*.txt') }}
-          restore-keys: |
-            ${{ runner.os }}-venv-
-
-      - name: Create env file
-        run: make envfile
+          python-version: 3.8.11
 
       - name: Install dependencies
         run: |
-          sudo apt install  python3-dev postgresql libpq-dev build-essential libxml2-dev libxslt1-dev postgresql
-          python -m pip install --upgrade pip
-
-      - uses: syphar/restore-virtualenv@v1
-        id: cache-virtualenv
-        with:
-          requirement_files: requirements*.txt  # this is optional
+          sudo apt install -y postgresql libpq-dev
+          make dev envfile
 
-      - uses: syphar/restore-pip-download-cache@v1
-        if: steps.cache-virtualenv.outputs.cache-hit != 'true'
+      - name: Validate code format
+        run: make check
 
-      - run: pip install -r requirements.txt -r requirements-dev.txt
-        if: steps.cache-virtualenv.outputs.cache-hit != 'true'
-    
-      # virtualenv is already activated
       - name: Setup database
         run: |
           sudo systemctl start postgresql
-          make postgres ACTIVATE=
+          make postgres
 
       - name: Run tests
-        run: make test ACTIVATE=
+        run: make test
         env:
           GH_TOKEN: 1