bazel: Use canonical reproducible load_bazlets rule

This silences the debug message:
  Rule 'com_googlesource_gerrit_bazlets' indicated that a canonical
  reproducible form can be obtained by modifying arguments shallow_since

Change-Id: I8c0a355d854db0a244be5b5febeda42c5b0ddae6

WORKSPACE

diff --git a/WORKSPACE b/WORKSPACE
index b648483..63c82f5 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -4,6 +4,7 @@
 
 load_bazlets(
     commit = "b6120a9fa50945d38f0a4d55d5879e3ec465c5e5",
+    shallow_since = "1701477032 -0700",
 )
 
 load(

bazlets.bzl

diff --git a/bazlets.bzl b/bazlets.bzl
index f089af4..457bfec 100644
--- a/bazlets.bzl
+++ b/bazlets.bzl
@@ -4,12 +4,14 @@
 
 def load_bazlets(
         commit,
+        shallow_since = None,
         local_path = None):
     if not local_path:
         git_repository(
             name = NAME,
             remote = "https://gerrit.googlesource.com/bazlets",
             commit = commit,
+            shallow_since = shallow_since,
         )
     else:
         native.local_repository(