build(python): drop support for Python 3.6 and 3.7 (#683)

BREAKING CHANGE: drop support for Python 3.6 and 3.7

Closes reanahub/reana#784

.github/workflows/ci.yml

@@ -55,7 +55,7 @@ jobs:
       - name: Setup Python
         uses: actions/setup-python@v5
         with:
-          python-version: 3.8
+          python-version: "3.8"
 
       - name: Check Python code formatting
         run: |
@@ -71,7 +71,7 @@ jobs:
       - name: Setup Python
         uses: actions/setup-python@v5
         with:
-          python-version: 3.8
+          python-version: "3.8"
 
       - name: Check compliance with pep8, pyflakes and circular complexity
         run: |
@@ -87,7 +87,7 @@ jobs:
       - name: Setup Python
         uses: actions/setup-python@v5
         with:
-          python-version: 3.8
+          python-version: "3.8"
 
       - name: Check compliance with Python docstring conventions
         run: |
@@ -103,7 +103,7 @@ jobs:
       - name: Setup Python
         uses: actions/setup-python@v5
         with:
-          python-version: 3.8
+          python-version: "3.8"
 
       - name: Check Python manifest completeness
         run: |
@@ -119,7 +119,7 @@ jobs:
       - name: Setup Python
         uses: actions/setup-python@v5
         with:
-          python-version: 3.8
+          python-version: "3.8"
 
       - name: Install system dependencies
         run: |
@@ -136,14 +136,15 @@ jobs:
 
   python-tests:
     runs-on: ubuntu-20.04
+
     steps:
       - name: Checkout
         uses: actions/checkout@v4
 
       - name: Setup Python
         uses: actions/setup-python@v5
         with:
-          python-version: 3.8
+          python-version: "3.8"
 
       - name: Install Python dependencies
         run: |

setup.py

@@ -139,6 +139,7 @@
         ],
     },
     include_package_data=True,
+    python_requires=">=3.8",
     extras_require=extras_require,
     install_requires=install_requires,
     setup_requires=setup_requires,