Disable branch coverage for e3-core

This is required in combination with COVERAGE_CORE=sysmon to speed up
coverage runs with Python >= 3.12.
See nedbat/coveragepy#1812

This was tentativly done by it/e3-core!76 as the option was not
found in the tox.ini template file.

ref it/cookiecutter-e3#73
ref it/e3-core#28

See merge request it/cookiecutter-e3!61 of the template

tox.ini

@@ -13,6 +13,14 @@ deps =
      codecov: codecov
 extras = test
 
+# Speed up coverage on Python >= 3.12
+setenv =
+  # Set COVERAGE_CORE only for Python >= 3.12
+  COVERAGE_CORE=sysmon
+  py311: COVERAGE_CORE=
+  py310: COVERAGE_CORE=
+  py39: COVERAGE_CORE=
+
 # Run testsuite with coverage when '-cov' and with multi-threading when '-xdist'
 # is in the env name
 commands=