refactor: drop github qualifiers from go

lib/datasource/go/index.js

@@ -10,7 +10,6 @@ module.exports = {
 function getGithubPurl(repo) {
   return {
     lookupName: repo.replace(/\/$/, ''),
-    qualifiers: {},
   };
 }
 

test/datasource/__snapshots__/go.spec.js.snap

@@ -18,19 +18,16 @@ Array [
   Array [
     Object {
       "lookupName": "x/text",
-      "qualifiers": Object {},
     },
   ],
   Array [
     Object {
       "lookupName": "x/text",
-      "qualifiers": Object {},
     },
   ],
   Array [
     Object {
       "lookupName": "go-x/x",
-      "qualifiers": Object {},
     },
   ],
 ]