feat: add script field to BuildStep message (#154)

- [ ] Regenerate this pull request now.

PiperOrigin-RevId: 392761119

Source-Link: googleapis/googleapis@3cd708e

Source-Link: googleapis/googleapis-gen@05d5619

google/cloud/devtools/cloudbuild_v1/types/cloudbuild.py

@@ -361,6 +361,10 @@ class BuildStep(proto.Message):
             this time, build step status is only updated on
             build completion; step status is not updated in
             real-time as the build progresses.
+        script (str):
+            A shell script to be executed in the step.
+            When script is provided, the user cannot specify
+            the entrypoint or args.
     """
 
     name = proto.Field(proto.STRING, number=1,)
@@ -376,6 +380,7 @@ class BuildStep(proto.Message):
     pull_timing = proto.Field(proto.MESSAGE, number=13, message="TimeSpan",)
     timeout = proto.Field(proto.MESSAGE, number=11, message=duration_pb2.Duration,)
     status = proto.Field(proto.ENUM, number=12, enum="Build.Status",)
+    script = proto.Field(proto.STRING, number=19,)
 
 
 class Volume(proto.Message):