exclude external from bazel coverage

[Mateusz-Krajewski]

How to modify this command to exclude from report external library like Processing file external/com_google_googletest/googlemock/include/gmock/gmock-cardinalities.h genhtml: ERROR: cannot read /home/matik/srp/external/com_google_googletest/googlemock/include/gmock/gmock-cardinalities.h
`bazel coverage //... -s
--instrument_test_targets
--experimental_cc_coverage
--combined_report=lcov
--instrumentation_filter="[:]"
--coverage_report_generator=@bazel_tools//tools/test/CoverageOutputGenerator/java/com/google/devtools/coverageoutputgenerator:Main > /dev/null 2>&1

lcov --summary bazel-out/_coverage/_coverage_report.dat

genhtml bazel-out/_coverage/_coverage_report.dat --output-directory coverage-report`