Fix casing of 'BEARER' to 'Bearer' in auth header

[yaronshanisima]

otherwise this seems to break oauth2 proxy https://github.com/oauth2-proxy/oauth2-proxy which will return 401 with the uppercase

Description

describe the purpose of the change here

Resolves <issue nr here>

PR Checklist

• Tests added
• Changelog updated

[davidradl]

@yaronshanisima thanks for your PR submission. Please could you raise in issue, add a change log entry and why you did not add tests. I have kicked off the tests, it seems the rest of the code uses the correct casing.

Once you fix up the PR, and the PR build works, I will get this merged

[davidradl]

Please add this change to the changelog, raise an issue and refer to it in this PR. I will then merge

[yaronshanisima]

This PR fixes #205.

Changes made:

• Fixed Bearer token casing from BEARER to Bearer in OIDCAuthHeaderValuePreprocessor.java to comply with RFC 6750
• Added changelog entry under [Unreleased] section
• Added unit tests using WireMock to verify the correct Bearer token casing

[davidradl]

@yaronshanisima ooking good, the format checker is saying :

Error: /home/runner/work/flink-http-connector/flink-http-connector/src/test/java/com/getindata/connectors/http/internal/OIDCAuthHeaderValuePreprocessorTest.java:1: File does not end with a newline. [NewlineAtEndOfFile]

Please could you amend.

[davidradl]

@yaronshanisima I see you put fixed in the change log, it should be under unreleased - I will change on my next commit.