Pin new dependency: github.com/google/cel-go v0.9.0

vendor/github.com/google/cel-go/ext/BUILD.bazel

@@ -0,0 +1,39 @@
+load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
+
+package(
+    licenses = ["notice"],  # Apache 2.0
+)
+
+go_library(
+    name = "go_default_library",
+    srcs = [
+        "encoders.go",
+        "guards.go",
+        "strings.go",
+    ],
+    importpath = "github.com/google/cel-go/ext",
+    visibility = ["//visibility:public"],
+    deps = [
+        "//cel:go_default_library",
+        "//checker/decls:go_default_library",
+        "//common/types:go_default_library",
+        "//common/types/ref:go_default_library",
+        "//interpreter/functions:go_default_library",
+        "@org_golang_google_genproto//googleapis/api/expr/v1alpha1:go_default_library",
+    ],
+)
+
+go_test(
+    name = "go_default_test",
+    size = "small",
+    srcs = [
+        "encoders_test.go",
+        "strings_test.go",
+    ],
+    embed = [
+        ":go_default_library",
+    ],
+    deps = [
+        "//cel:go_default_library",
+    ],
+)