Update onnx package version minimum to 1.16.0.

.github/workflows/ci.yml

@@ -621,7 +621,7 @@ jobs:
           pip install --upgrade pip
           # Pre-fetch optional deps that iree-compiler needs (but we constrain that
           # to not consult a package index).
-          pip install onnx>=1.15.0
+          pip install onnx>=1.16.0
           pip install --no-index -f $PWD -v iree-compiler[onnx]
           echo "Testing default compiler:"
           python -m iree.compiler._package_test

compiler/setup.py

@@ -467,7 +467,7 @@ def find_git_submodule_revision(submodule_path):
     ],
     extras_require={
         "onnx": [
-            "onnx>=1.15.0",
+            "onnx>=1.16.0",
         ],
     },
 )