[chore] Update Go version to 1.18 (#444)

* linting with new golangci-lint version

* update go to 1.18

* bump versions in drone.yml

* use new runtime/debug package for version info

* remove Commit build flag from goreleaser

* remove mock commit + version from build script

* go fmt

* add dummy version env flag to test container

* install git in golang container for testing

* only set versionString if Version is defined

internal/processing/streaming/streamdelete.go

@@ -31,7 +31,12 @@ func (p *processor) StreamDelete(statusID string) error {
 	// get all account IDs with open streams
 	accountIDs := []string{}
 	p.streamMap.Range(func(k interface{}, _ interface{}) bool {
-		accountIDs = append(accountIDs, k.(string))
+		key, ok := k.(string)
+		if !ok {
+			panic("streamMap key was not a string (account id)")
+		}
+
+		accountIDs = append(accountIDs, key)
 		return true
 	})