Add removable-media interface plug declaration to the snap packaging(m…

…ikefarah#1618)

Allow snap users to process YAML documents under /media or /mnt paths after connecting to the `removable-media` snapd slot:

```
sudo snap connect yq :removable-media
```

Fixes mikefarah#1618.

snap/snapcraft.yaml

@@ -9,7 +9,7 @@ confinement: strict
 apps:
   yq:
     command: yq
-    plugs: [home]
+    plugs: [home, removable-media]
 parts:
   yq:
     plugin: go