drop dependency on setuptools at runtime to enumerate entrypoints

pkg_resources is deprecated and the recommended replacement is to use
importlib.metadata where relevant. The result is faster to load, and
more guaranteed to work e.g. in environments where setuptools isn't
installed by default.

pifpaf/__main__.py

@@ -13,6 +13,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import importlib.metadata
 import logging
 import operator
 import os
@@ -26,8 +27,6 @@
 
 import fixtures
 
-import pkg_resources
-
 import psutil
 
 from pifpaf import util
@@ -69,8 +68,10 @@ def _format_multiple_exceptions(e, debug=False):
                 LOG.error(value)
 
 
-DAEMONS = list(map(operator.attrgetter("name"),
-                   pkg_resources.iter_entry_points("pifpaf.daemons")))
+if sys.version_info >= (3, 10):
+    DAEMONS = importlib.metadata.entry_points(group='pifpaf.daemons')
+else:
+    DAEMONS = importlib.metadata.entry_points()['pifpaf.daemons']
 
 
 @click.group()
@@ -83,7 +84,7 @@ def _format_multiple_exceptions(e, debug=False):
 @click.option("--global-urls-variable", "-g",
               help="global variable name to use to append connection URL  "
               "when chaining multiple pifpaf instances (default: PIFPAF_URLS)")
-@click.version_option(pkg_resources.get_distribution('pifpaf').version)
+@click.version_option(importlib.metadata.distribution('pifpaf').version)
 @click.pass_context
 def main(ctx, verbose=False, debug=False, log_file=None,
          env_prefix=None, global_urls_variable=None):
@@ -119,19 +120,18 @@ def main(ctx, verbose=False, debug=False, log_file=None,
 
 @main.command(name="list")
 def drivers_list():
-    for n in DAEMONS:
+    for n in DAEMONS.keys():
         click.echo(n)
 
 
 class RunGroup(click.MultiCommand):
     @staticmethod
     def list_commands(ctx):
-        return DAEMONS
+        return DAEMONS.keys()
 
     def get_command(self, ctx, name):
         params = [click.Argument(["command"], nargs=-1)]
-        plugin = pkg_resources.load_entry_point(
-            "pifpaf", "pifpaf.daemons", name)
+        plugin = [e for e in DAEMONS if e.name == name][0].load()
         params.extend(map(lambda kw: click.Option(**kw), plugin.get_options()))
 
         def _run_cb(*args, **kwargs):