tools/ci.sh: Use CPython 3.11 for Unix/RV64.

This commit forces the installation of CPython 3.11 instead of CPython
3.12 in the OS image for Unix/RV64 CI jobs.

CPython 3.12 is not compatible with settrace tests, but it is the
CPython version that is installed by default in "ubuntu-latest" (which
is Ubuntu 24.04 LTS right now).  Updating the base image for the RV64
tests also disabled settrace tests to work around its incompatibility,
however turns out there is a way to force CI to set up a base OS image
with an arbitrary CPython version.

Now the RV64 CI jobs are now going to be executed using CPython 3.11,
and thus the settrace tests can be removed from the ignore list.

Signed-off-by: Alessandro Gatti <a.gatti@frob.it>

.github/workflows/ports_unix.yml

@@ -288,6 +288,11 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v6
+    - uses: actions/setup-python@v6
+      # Python 3.12 is the default for ubuntu-24.04, but that has compatibility issues with settrace tests.
+      # Can remove this step when ubuntu-latest uses a more recent Python 3.x as the default.
+      with:
+        python-version: '3.11'
     - name: Install packages
       run: tools/ci.sh unix_qemu_riscv64_setup
     - name: Build

tools/ci.sh

@@ -961,8 +961,8 @@ function ci_unix_qemu_riscv64_setup {
     ci_gcc_riscv_setup
     sudo apt-get update
     sudo apt-get install gcc-riscv64-linux-gnu g++-riscv64-linux-gnu libltdl-dev
-    sudo pip3 install pyelftools
-    sudo pip3 install ar
+    python3 -m pip install pyelftools
+    python3 -m pip install ar
     sudo apt-get install qemu-user-static
     qemu-riscv64-static --version
     sudo mkdir -p /usr/gnemul
@@ -977,13 +977,12 @@ function ci_unix_qemu_riscv64_build {
 
 function ci_unix_qemu_riscv64_run_tests {
     # Issues with RISCV-64 tests:
-    # - misc/sys_settrace_features.py doesn't work with CPython 3.12
     # - thread/stress_aes.py takes around 180 seconds
     # - thread/stress_recurse.py is flaky
     # - thread/thread_gc1.py is flaky
     file ./ports/unix/build-coverage/micropython
     pushd tests
-    MICROPY_MICROPYTHON=../ports/unix/build-coverage/micropython MICROPY_TEST_TIMEOUT=200 ./run-tests.py --exclude 'misc/sys_settrace_features.py|thread/stress_recurse.py|thread/thread_gc1.py'
+    MICROPY_MICROPYTHON=../ports/unix/build-coverage/micropython MICROPY_TEST_TIMEOUT=200 ./run-tests.py --exclude 'thread/stress_recurse.py|thread/thread_gc1.py'
     MICROPY_MICROPYTHON=../ports/unix/build-coverage/micropython ./run-natmodtests.py extmod/btree*.py extmod/deflate*.py extmod/framebuf*.py extmod/heapq*.py extmod/random_basic*.py extmod/re*.py
     popd
 }