Check license issues only in current OS

Dashboard summarizes license issues by checking the copyright report for
all the available branches. This works fine in Apertis since the filter
for releases newer than v2021 also filters Debian branches.

On downstreams from Apertis, this filter allows the same issue to be reported
both in apertis and downstream branch, creating lot of noise.

Improve the filtering to only take into account the branches for the current
OS.

Signed-off-by: Walter Lozano <walter.lozano@collabora.com>

bin/packaging-data-fetch-downstream

@@ -363,6 +363,8 @@ class DownstreamFetcher:
 
         def _fetch_license_report(project):
             for branch in project.branches.values():
+                if branch.name not in self.channels:
+                    continue
                 release = branch.name.split("/")[-1].split("-")[0]
                 if release < "v2021":
                     # prior to v2021 the component was not tracked in git