Update upb dep to the latest 23.x commit (#13215)

* Update upb dep to the latest 23.x commit

* Fix objectivec test failure in Bazel 6+.

This fix works in Bazel 5 and 6, but the original `import pddm` only works in Bazel 5.  This is preventing our upgrade to Bazel 6 that will reduce our mac flakes in CI.

PiperOrigin-RevId: 543565397

* Bump heap size for linkage monitor tests

.github/workflows/test_java.yml

@@ -72,7 +72,7 @@ jobs:
       - name: Download Linkage Monitor
         run: curl -v -O "https://storage.googleapis.com/cloud-opensource-java-linkage-monitor/linkage-monitor-latest-all-deps.jar"
       - name: Fails if there's new linkage errors compared with baseline
-        run: java -Xmx2048m -jar linkage-monitor-latest-all-deps.jar com.google.cloud:libraries-bom
+        run: java -Xmx4096m -jar linkage-monitor-latest-all-deps.jar com.google.cloud:libraries-bom
 
   protobuf-bom:
     name: Protobuf Maven BOM

objectivec/DevTools/pddm_tests.py

@@ -35,7 +35,7 @@
 import io
 import unittest
 
-import pddm
+from objectivec.DevTools import pddm
 
 
 class TestParsingMacros(unittest.TestCase):

protobuf_deps.bzl

@@ -151,7 +151,7 @@ def protobuf_deps():
         _github_archive(
             name = "upb",
             repo = "https://github.com/protocolbuffers/upb",
-            commit = "1956df14832979471d0c79210a817aeb54f7a526",
-            sha256 = "102039feae921205690d28561d6c74ba13e0561a76d7247de5df7d7cc8d72ca6",
+            commit = "455cfdb8ae60a1763e6d924e36851c6897a781bb",
+            sha256 = "2c8b4e961c38fcc7c58e8aca807cc3cc5190f42afdf39551ce49812b130493de",
             patches = ["@com_google_protobuf//build_defs:upb.patch"],
         )