Remove sysmon coverage core setting

Coverage.py will now error if incompatible settings are used. In our
case, this is the `branch` setting.

Coverage on Python 3.14+ should automatically use sysmon.

Author: Stormheg

.github/workflows/test.yml

@@ -11,7 +11,6 @@ env:
   FORCE_COLOR: "1" # Make tools pretty.
   TOX_TESTENV_PASSENV: FORCE_COLOR
   PIP_DISABLE_PIP_VERSION_CHECK: "1"
-  COVERAGE_CORE: sysmon # Only supported on Python 3.12+, ignore on older versions
   PYTHON_LATEST: "3.14"
 
 jobs: