ci: always use latest Python version supported by Red-DiscordBot

Author: tigattack

.github/actions/setup/action.yml

@@ -3,10 +3,16 @@ description: Installs project dependencies
 runs:
   using: composite
   steps:
+    - name: Find latest Python supported by Red-DiscordBot
+      id: find_pyver
+      shell: bash
+      run: |
+        PYVER=$(bash .github/actions/setup/find_latest_red_pyver.sh)
+        echo "python-version=$PYVER" >> "$GITHUB_OUTPUT"
     - name: Set up Python
       uses: actions/setup-python@v5
       with:
-        python-version: "3.11"
+        python-version: ${{ steps.find_pyver.outputs.python-version }}
     - name: Install base dependencies
       shell: bash
       run: pip install --quiet --upgrade --requirement requirements.txt

.github/find_latest_red_pyver.sh

@@ -0,0 +1,29 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+PACKAGE="Red-DiscordBot"
+
+# Fetch requires_python string, e.g. ">=3.9,<3.13"
+REQUIRES=$(curl -s "https://pypi.org/pypi/${PACKAGE}/json" | jq -r '.info.requires_python')
+
+# Extract lower and upper bounds
+LOWER=$(grep -oP '(?<=\>=)[0-9]+\.[0-9]+' <<<"$REQUIRES" || true)
+UPPER=$(grep -oP '(?<=\<)[0-9]+\.[0-9]+' <<<"$REQUIRES" | head -n1 || true)
+
+# Get all active Python versions from endoflife.date API
+VERSIONS=$(curl -s https://endoflife.date/api/python.json | jq -r '.[].latest' | cut -d. -f1,2 | sort -Vu)
+
+# Filter by lower/upper bounds
+SUPPORTED=$(echo "$VERSIONS" | while read v; do
+    if [[ -n "$LOWER" && "$(printf '%s\n' "$v" "$LOWER" | sort -V | head -n1)" != "$LOWER" ]]; then
+        continue
+    fi
+    if [[ -n "$UPPER" && "$(printf '%s\n' "$v" "$UPPER" | sort -V | head -n1)" == "$UPPER" ]]; then
+        continue
+    fi
+    echo "$v"
+done)
+
+LATEST=$(echo "$SUPPORTED" | sort -V | tail -n1)
+
+echo "$LATEST"

.github/workflows/ci.yml

@@ -23,10 +23,11 @@ jobs:
       - name: Checkout the repository at the current branch
         uses: actions/checkout@v4
       - name: Install dependencies
+        id: setup_deps
         uses: ./.github/actions/setup
       - uses: jakebailey/pyright-action@v2
         with:
-          python-version: "3.11"
+          python-version: ${{ steps.setup_deps.outputs.python-version }}
 
   check-json:
     runs-on: ubuntu-latest