Add wait step as a separate one.

Signed-off-by: Jacob Kiers <jacob@jacobkiers.net>

.drone.jsonnet

@@ -17,7 +17,6 @@ local buildForArch(arch) = {
   }],
   commands: [
     'echo Hello World from Jsonnet on ' + arch + '!',
-    'while ! docker image ls; do sleep 1; done',
     'cross build --release --target ' + arch,
     'rm -rf target/' + arch + '/release/{build,deps,examples,incremental}',
     'ls -lah target/' + arch + '/release',
@@ -40,7 +39,12 @@ local check_steps() = [
     arch: 'amd64',
   },
   steps:
-    check_steps() +
+    [{
+      name: 'wait-for-docker',
+      image: 'rust:1.62',
+      commands: ['while ! docker image ls; do sleep 1; done'],
+    }]
+    + check_steps() +
     [
       {
         name: 'build',