Update git submodules

* Update plugins/delete-project from branch 'stable-3.1'
  to 5296f452067ba54f3546edee879b91338a8dfc34
  - ErrorProne: Fix UnusedException errors
    
    When the UnusedException check is enabled, the build fails with:
    
      [UnusedException] This catch block catches an symbol and re-throws
      another, but swallows the caught symbol rather than setting it as a
      cause. This can make debugging harder.
    
    Fix it by setting the caught exception as cause on the subsequently
    thrown exception.
    
    Note: The grammatically incorrect error message is copy-pasted as-is
    from the version of ErrorProne currently used in Bazel; it has been
    fixed by [1] in the latest version.
    
    [1] https://github.com/google/error-prone/commit/d57a39c
    
    Change-Id: I0139249b992e70e47db1f8213dbc8ce80c445128
    
diff --git a/plugins/delete-project b/plugins/delete-project
index 4cbdd07..5296f45 160000
--- a/plugins/delete-project
+++ b/plugins/delete-project
@@ -1 +1 @@
-Subproject commit 4cbdd07982bb15756c27bc11a77d6b67428006fc
+Subproject commit 5296f452067ba54f3546edee879b91338a8dfc34