Add possibility to deselect resources with tags

[travenin]

Describe the Feature

I want to select all features as default, but unselect some resources with tags. I though I could use selection_tags for this:

  backup_resources = ["*"]
  selection_tags = [
    {
      type  = "STRINGNOTEQUALS"
      key   = "disable_backup"
      value = "true"
    }
  ]

Expected Behavior

The backup plan should have conditions to select all resources except those with a tag disable_backup = true.

Currently (v1.0.2) I get an error that only string equals is supported as selection condition:

Error: expected type to be one of ["STRINGEQUALS"], got STRINGNOTEQUALS

with module.backup.module.backup.aws_backup_selection.default[0],
on .terraform/modules/backup.backup/main.tf line 134, in resource "aws_backup_selection" "default":
134: resource "aws_backup_selection" "default" {

Use Case

It would be handy to select all resources and then opt out some resources from backups.

Describe Ideal Solution

Support string_not_equals type of condition.

Alternatives Considered

No response

Additional Context

No response