Merge pull request #345 from voxpupuli/maint/drop-eol-os-debian9

drop support for debian 9 (EOL)

Author: jhoblitt

metadata.json

@@ -51,7 +51,6 @@
     {
       "operatingsystem": "Debian",
       "operatingsystemrelease": [
-        "9",
         "10"
       ]
     },