Update gcp-cloudbuild-privesc.md removing cloudbuild.builds.update

### `cloudbuild.builds.update`

Currently this permission is listed to **only** be able to be used to use the api method `builds.cancel()` which cannot be abused to change the parameters of an ongoing build

References:
- https://cloud.google.com/build/docs/iam-roles-permissions#permissions
- https://cloud.google.com/build/docs/api/reference/rest/v1/projects.builds/cancel

Author: hasshido

src/pentesting-cloud/gcp-security/gcp-privilege-escalation/gcp-cloudbuild-privesc.md

@@ -37,11 +37,6 @@ You can find the original exploit script [**here on GitHub**](https://github.com
 
 For a more in-depth explanation, visit [https://rhinosecuritylabs.com/gcp/iam-privilege-escalation-gcp-cloudbuild/](https://rhinosecuritylabs.com/gcp/iam-privilege-escalation-gcp-cloudbuild/)
 
-### `cloudbuild.builds.update`
-
-**Potentially** with this permission you will be able to **update a cloud build and just steal the service account token** like it was performed with the previous permission (but unfortunately at the time of this writing I couldn't find any way to call that API).
-
-TODO
 
 ### `cloudbuild.repositories.accessReadToken`