tests: run mvdan/shfmt on test runs

While I do not agree with _every_ style change, this will force Dokku to have consistent formatting across all shell scripts, which is arguably a Good Thing™.

The command used to reprocess everything is:

```shell
shfmt -l -bn -ci -i 2 -w .
```

plugins/apps/subcommands/locked

@@ -1,5 +1,6 @@
 #!/usr/bin/env bash
-set -eo pipefail; [[ $DOKKU_TRACE ]] && set -x
+set -eo pipefail
+[[ $DOKKU_TRACE ]] && set -x
 source "$PLUGIN_CORE_AVAILABLE_PATH/common/functions"
 source "$PLUGIN_AVAILABLE_PATH/apps/internal-functions"
 
@@ -7,10 +8,11 @@ apps_locked_cmd() {
   declare desc="checks if an app is locked for deployment"
   declare cmd="apps:locked"
   [[ "$1" == "$cmd" ]] && shift 1
-  declare APP="$1"; verify_app_name "$APP"
+  declare APP="$1"
+  verify_app_name "$APP"
   local LOCKED="$(apps_is_locked "$APP")"
 
-  if [[ "$LOCKED" != "true" ]] ; then
+  if [[ "$LOCKED" != "true" ]]; then
     dokku_log_fail_quiet "Deploy lock does not exist"
   fi