Allow python_requirements_facts to cope with packages with dashes

```
python_requirements_facts:
  dependencies:
    - kubernetes-validate
```

should work as expected

changelogs/fragments/python_requirements_facts_dashes.yml

@@ -0,0 +1,2 @@
+bugfixes:
+  - allow python_requirements_facts to report on dependencies containing dashes

lib/ansible/modules/system/python_requirements_facts.py

@@ -123,7 +123,7 @@ def main():
             python_version=sys.version,
             python_system_path=sys.path,
         )
-    pkg_dep_re = re.compile(r'(^[a-zA-Z][a-zA-Z0-9_]+)(==|[><]=?)?([0-9.]+)?$')
+    pkg_dep_re = re.compile(r'(^[a-zA-Z][a-zA-Z0-9_-]+)(==|[><]=?)?([0-9.]+)?$')
 
     results = dict(
         not_found=[],