Add Python 3.12 to CI

Define a separate set of dependency versions for Python 3.12 since it's so new
and requires much newer minimum library versions than other Python versions.

.github/workflows/main.yml

@@ -26,7 +26,7 @@ jobs:
       fail-fast: false
       matrix:
         os: ['ubuntu-22.04']
-        python: ['3.8', '3.9', '3.10', '3.11']
+        python: ['3.8', '3.9', '3.10', '3.11', '3.12']
 
     runs-on: ${{ matrix.os }}
     name: ${{ matrix.os }} with Python ${{ matrix.python }}
@@ -42,8 +42,13 @@ jobs:
         python-version: ${{ matrix.python }}
         cache: 'pip'
 
-    - name: Install Python core deps
+    - name: Install Python core deps (3.8 — 3.11)
       run: python -m pip install -r requirements.txt
+      if: ${{ matrix.python != '3.12' }}
+
+    - name: Install Python core deps (3.12)
+      run: python -m pip install -r requirements-3.12.txt
+      if: ${{ matrix.python == '3.12' }}
 
     - name: Install Python testing deps
       run: python -m pip install -r requirements-test.txt

requirements-3.12.txt

@@ -0,0 +1,6 @@
+# These requirements are specifically for Python 3.12; earlier Python versions
+# accept the dependency versions in `requirements.txt`.
+
+tensorflow ~= 2.16.1
+keras ~= 3.0.0
+numpy ~= 1.24.0

requirements.txt

@@ -1,3 +1,6 @@
+# These versions are compatible for Python 3.8-3.11; Python 3.12 has its own
+# dependency versions defined in `requirements-3.12.txt`.
+
 tensorflow ~= 2.12.0
 keras ~= 2.12.0
 numpy ~= 1.24.0