Wait for the Docker daemon to be ready before starting act runner (#620)

Follow #619.

Wait for the Docker daemon to be ready before starting act runner.

Reviewed-on: https://gitea.com/gitea/act_runner/pulls/620
Co-authored-by: Jason Song <i@wolfogre.com>
Co-committed-by: Jason Song <i@wolfogre.com>

scripts/s6/act_runner/finish

@@ -1,4 +1,3 @@
 #!/usr/bin/env bash
 
 exec s6-svscanctl -t /etc/s6
-

scripts/s6/act_runner/run

@@ -1,3 +1,5 @@
 #!/usr/bin/env bash
 
+s6-svwait -U /etc/s6/docker
+
 exec run.sh