github/workflows: Use Python 3.11 for unix coverage testing.

This removes the need for an explicit `sys_settrace_features.py.exp` file.

This means that people testing locally will also need to install Python
3.11 in some way, such as with pyenv or uv, and use it during
`make VARIANT=coverage test`, or they will get failures.

When using Python from GitHub actions/setup-python, pip3 can't be wrapped
by sudo, because this invokes the operating system python instead.

Signed-off-by: Jeff Epler <jepler@gmail.com>

tools/ci.sh

@@ -612,9 +612,9 @@ function ci_unix_standard_v2_run_tests {
 }
 
 function ci_unix_coverage_setup {
-    sudo pip3 install setuptools
-    sudo pip3 install pyelftools
-    sudo pip3 install ar
+    pip3 install setuptools
+    pip3 install pyelftools
+    pip3 install ar
     gcc --version
     python3 --version
 }