chore(deps): update dependency com_google_protobuf to v3.12.0-rc2 (#389)
chore(deps): update dependency com_google_protobuf to v3.12.0-rc2 (#389)

This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [com_google_protobuf](https://togithub.com/protocolbuffers/protobuf) | http_archive | patch | `v3.12.0-rc1` -> `v3.12.0-rc2` |

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### Release Notes

<details>
<summary>protocolbuffers/protobuf</summary>

### [`v3.12.0-rc2`](https://togithub.com/protocolbuffers/protobuf/releases/v3.12.0-rc2)

[Compare Source](https://togithub.com/protocolbuffers/protobuf/compare/v3.12.0-rc1...v3.12.0-rc2)

### C++ / Python

-   Fix for [#&#8203;7463](https://togithub.com/protocolbuffers/protobuf/issues/7463) ("mixing with optional fields: core dump --experimental_allow_proto3_optional")

### Java

-   Fix for [#&#8203;7480](https://togithub.com/protocolbuffers/protobuf/issues/7480) ("TextFormat and JsonFormat ignore experimental proto3 optional enums")

### PHP

-   Ignore unknown enum value when ignore_unknown specified ([#&#8203;7455](https://togithub.com/protocolbuffers/protobuf/issues/7455))

### C

-   Mark GetOption API as obsolete and expose the "GetOptions()" method on descriptors instead ([#&#8203;7491](https://togithub.com/protocolbuffers/protobuf/issues/7491))
-   Remove Has/Clear members for C# message fields in proto2 ([#&#8203;7429](https://togithub.com/protocolbuffers/protobuf/issues/7429))

</details>

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