Update rds engine version in terraform deployments (#785)

Update rds engine version to 8.0.33

**Which issue is resolved by this Pull Request:**
Resolves #

**Description of your changes:**
Updates rds engine version

**Testing:**
- [ ] Unit tests pass
- [x] e2e tests pass - rds/s3 test passed
- Details about new tests (If this PR adds a new feature)
- Details about any manual tests performed

```
PASSED
--
5932 | tests/terraform/test_rds_s3.py::TestRDSS3Terraform::test_verify_mlpipeline_db PASSED
5933 | tests/terraform/test_rds_s3.py::TestRDSS3Terraform::test_verify_mlmdb PASSED
5934 | tests/terraform/test_rds_s3.py::TestRDSS3Terraform::test_s3_bucket_is_being_used_as_metadata_store PASSED
5935 | tests/terraform/test_rds_s3.py::TestRDSS3Terraform::test_kfp_experiment Forwarding from 127.0.0.1:8080 -> 8080
5936 | Handling connection for 8080
5937 | Handling connection for 8080
5938 |  
5939 | -------------------------------- live log call ---------------------------------
5940 | INFO     root:_client.py:456 Creating experiment experiment-mqe8btvlg5.
5941 | PASSED
5942 | tests/terraform/test_rds_s3.py::TestRDSS3Terraform::test_run_pipeline
5943 | -------------------------------- live log call ---------------------------------
5944 | INFO     root:_client.py:456 Creating experiment experiment-iv8yyghl65.
5945 | PASSED
```

By submitting this pull request, I confirm that my contribution is made
under the terms of the Apache 2.0 license.

iaac/terraform/aws-infra/rds/variables.tf

@@ -45,7 +45,7 @@ variable "db_allocated_storage" {
 variable "mysql_engine_version" {
   type        = string
   description = "The engine version of MySQL"
-  default     = "8.0.32"
+  default     = "8.0.33"
 }
 
 variable "backup_retention_period" {
@@ -93,4 +93,4 @@ variable "tags" {
   description = "Additional tags (e.g. `map('BusinessUnit`,`XYZ`)"
   type        = map(string)
   default     = {}
-}
+}