Fix coverage scan of the native namespace package

The coverage bug reported in:
- nedbat/coveragepy#566
- nedbat/coveragepy#1024
- nedbat/coveragepy#1383

Fix available in >=7.0.0, via `include_namespace_packages` config option.

Author: randomir

.coveragerc

@@ -6,6 +6,7 @@ omit =
     dwave/cloud/package_info.py
 
 [report]
+include_namespace_packages = True
 exclude_lines =
     pragma: no cover
     raise NotImplementedError

tests/requirements.txt

@@ -1,4 +1,4 @@
 requests_mock>=1.8
-coverage
+coverage>=7.0.0     # native namespace package support added in 7.0.0
 parameterized
 dwave-networkx