chore: add missing deprecation message (#2451)

Author: sfc-gh-jcieslak

pkg/resources/database_grant.go

@@ -86,7 +86,8 @@ func DatabaseGrant() *TerraformGrantResource {
 			Delete: DeleteDatabaseGrant,
 			Update: UpdateDatabaseGrant,
 
-			Schema: databaseGrantSchema,
+			DeprecationMessage: "This resource is deprecated and will be removed in a future major version release. Please use snowflake_grant_privileges_to_account_role instead.",
+			Schema:             databaseGrantSchema,
 			Importer: &schema.ResourceImporter{
 				StateContext: func(ctx context.Context, d *schema.ResourceData, m interface{}) ([]*schema.ResourceData, error) {
 					parts := strings.Split(d.Id(), helpers.IDDelimiter)