Update git submodules

* Update plugins/delete-project from branch 'master'
  to 180fd9dbd7f1661d16bf05ca8a16c74bfcc9bc67
  - Merge branch 'stable-3.1'
    
    * stable-3.1:
      ErrorProne: Fix UnusedException errors
    
    Change-Id: Ie0fe8faafd9682d2a3f1620a669edc1f527ad283
    
  - 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 7885a9f..180fd9d 160000
--- a/plugins/delete-project
+++ b/plugins/delete-project
@@ -1 +1 @@
-Subproject commit 7885a9fa8d262b6127a7a3aa294108d6aac47a4d
+Subproject commit 180fd9dbd7f1661d16bf05ca8a16c74bfcc9bc67