Add Python 3.9 and drop 3.7 support

Python 3.7 reached the end-of-life phase on 2023-06-27
and is no longer supported.
The GitHub workflows now test for Python 3.9 instead
of 3.7.

Signed-off-by: Eva Millán <evamillan@bitergia.com>

.github/workflows/release.yml

@@ -46,7 +46,7 @@ jobs:
     name: Python ${{ matrix.python-version }}
     strategy:
       matrix:
-        python-version: [3.7, 3.8]
+        python-version: [3.8, 3.9]
 
     steps:
       - uses: actions/checkout@93ea575cb5d8a053eaa0ac8fa3b40d7e05a33cc8 # 3.1.0

.github/workflows/tests.yml

@@ -25,7 +25,7 @@ jobs:
 
     strategy:
       matrix:
-        python-version: [3.7, 3.8]
+        python-version: [3.8, 3.9]
 
     runs-on: ubuntu-latest
     name: Python ${{ matrix.python-version }}
@@ -96,7 +96,7 @@ jobs:
     strategy:
       matrix:
         node-version: [16.x]
-        python-version: [3.7, 3.8]
+        python-version: [3.8, 3.9]
 
     runs-on: ubuntu-latest
     name: Node ${{ matrix.node-version }} Python ${{ matrix.python-version }}

README.md

@@ -15,10 +15,10 @@ In the context of GrimoireLab, Sorting Hat is usually run after data is retrieve
 
 ## Requirements
 
-* Python >= 3.7
+* Python >= 3.8
 * Poetry >= 1.1.0
 * MySQL >= 5.7 or MariaDB 10.0
-* Django = 3.1
+* Django = 3.2
 * Graphene-Django >= 2.0
 * uWSGI >= 2.0