terraform: upgrade to latest GCP provider version

Change-Id: Ie6a5fc3ffc1f5bb75395029112f806de502460e1
Reviewed-on: https://go-review.googlesource.com/c/pkgsite-metrics/+/473776
Reviewed-by: Zvonimir Pavlinovic <zpavlinovic@google.com>
Run-TryBot: Jonathan Amsterdam <jba@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
diff --git a/terraform/main.tf b/terraform/main.tf
index 81f0327..a2e2093 100644
--- a/terraform/main.tf
+++ b/terraform/main.tf
@@ -12,7 +12,7 @@
   }
   required_providers {
     google = {
-      version = "~> 3.90.1"
+      version = "~> 4.55.0"
       source  = "hashicorp/google"
     }
   }