Turn pathlib paths into strs

Some APIs do not take a pathlib.  They need to have a string
representation of a path.  Transform the default path to a str
so those APIs will work with the default value.

hacking/build_library/build_ansible/command_plugins/collection_meta.py

@@ -42,7 +42,7 @@ class DocumentCollectionMeta(Command):
                             default=DEFAULT_TEMPLATE_FILE,
                             help="Jinja2 template to use for the config")
         parser.add_argument("-T", "--template-dir", action="store", dest="template_dir",
-                            default=DEFAULT_TEMPLATE_DIR,
+                            default=str(DEFAULT_TEMPLATE_DIR),
                             help="directory containing Jinja2 templates")
         parser.add_argument("-o", "--output-dir", action="store", dest="output_dir", default='/tmp/',
                             help="Output directory for rst files")

hacking/build_library/build_ansible/command_plugins/dump_config.py

@@ -46,7 +46,7 @@ class DocumentConfig(Command):
                             default=DEFAULT_TEMPLATE_FILE,
                             help="Jinja2 template to use for the config")
         parser.add_argument("-T", "--template-dir", action="store", dest="template_dir",
-                            default=DEFAULT_TEMPLATE_DIR,
+                            default=str(DEFAULT_TEMPLATE_DIR),
                             help="directory containing Jinja2 templates")
         parser.add_argument("-o", "--output-dir", action="store", dest="output_dir", default='/tmp/',
                             help="Output directory for rst files")