Fix future release date (jaegertracing#5146)

## Which problem is this PR solving?

## Description of the changes
Change the Tentative release date for version 1.57.0 to 1 May 2024

## How was this change tested?
- 

## Checklist
- [ ] I have read
https://github.com/jaegertracing/jaeger/blob/master/CONTRIBUTING_GUIDELINES.md
- [ ] I have signed all commits
- [ ] I have added unit tests for the new functionality
- [ ] I have run lint and test steps successfully
  - for `jaeger`: `make lint test`
  - for `jaeger-ui`: `yarn lint` and `yarn test`

Signed-off-by: Axkea <2832468078@qq.com>

RELEASE.md

@@ -58,4 +58,4 @@ Here are the release managers for future versions with the tentative release dat
 | 1.54.0  | @joe-elliott    | 7 February 2024        |
 | 1.55.0  | @jkowall        | 6 March 2024           |
 | 1.56.0  | @yurishkuro     | 3 April 2024           |
-| 1.57.0  | @albertteoh     | 1 May 2023             |
+| 1.57.0  | @albertteoh     | 1 May 2024             |