chore(deps): update terraform oci to v6.20.0 (#26)

This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [oci](https://registry.terraform.io/providers/oracle/oci)
([source](https://redirect.github.com/oracle/terraform-provider-oci)) |
required_provider | minor | `6.18.0` -> `6.20.0` |

---

### Release Notes

<details>
<summary>oracle/terraform-provider-oci (oci)</summary>

###
[`v6.20.0`](https://redirect.github.com/oracle/terraform-provider-oci/blob/HEAD/CHANGELOG.md#6200-December-11-2024)

[Compare
Source](https://redirect.github.com/oracle/terraform-provider-oci/compare/v6.19.0...v6.20.0)

##### Added

-   Support for Fleet Application Management Service v1.2
-   Support for BYOK for ADB-D
-   Support for Rollback Maintenance Cycle Feature
-   Support for Data Flow CascadeDeleteApplication API
-   Support for refresh DR Plans
-   Support for Private Access to a VB service instance

##### Bug Fix

-   Fix for the vm network update in place issue
-   Fix Instance Configuration Config Mapping
-   Fix for MySQL Cross Region Copy Backup Destroy
- Incorporated more workrequest status for createSchedule and
updateSchedule workflow
- Support for Wwether the volumes are preserved when a desktop pool is
deleted

###
[`v6.19.0`](https://redirect.github.com/oracle/terraform-provider-oci/blob/HEAD/CHANGELOG.md#6190-November-21-2024)

[Compare
Source](https://redirect.github.com/oracle/terraform-provider-oci/compare/v6.18.0...v6.19.0)

##### Added

-   README.md of service examples with magic button
-   Release for v6.18.0
-   Support for Add secretIds for sensitive connection attributes
-   Support for Oracle Cloud AI Service Generative AI Agent Service

</details>

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terraform/oci/versions.tf

@@ -8,7 +8,7 @@ terraform {
   required_providers {
     oci = {
       source  = "oracle/oci"
-      version = "6.18.0"
+      version = "6.20.0"
     }
   }
 }