When I set this up originally, it create the Aurora cluster with the defined version. It appears that AWS has upgraded it in the background. Since I'm calling this as a module, I can't use lifecycle to ignore the change and move. This will likely prevent any future deploys.

Untested (I might tomorrow) but engine_version supports partials, which should allow AWS to do the forced upgrades without breaking things.

 # module.serverless-static-wordpress.aws_rds_cluster.serverless_wordpress will be updated in-place
 ~ resource "aws_rds_cluster" "serverless_wordpress" {
 ~ engine_version = "5.7.mysql_aurora.2.08.3" -> "5.7.mysql_aurora.2.07.1"
 id = "site-serverless-wordpress"
 tags = {}
 # (36 unchanged attributes hidden)
 # (1 unchanged block hidden)
 }