Fix: Ensure Content-Type is set based on header value if not explicit…

[KyrillosNageh]

Fixes #1697

This PR ensures that the Content-Type is set based on the header value if it is not explicitly set by the user.

• Modified the prepareRequestSpecs method to check if contentType is still ContentType.ANY.
• If ContentType is not explicitly set by the user, it now retrieves the Content-Type from sessionHeaders and applies it directly to the RequestSpecBuilder.
• This change ensures that the request uses the exact Content-Type provided in the headers, preventing encoding and serialization issues.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 83.33333% with 1 line in your changes missing coverage. Please review.

Project coverage is 53.95%. Comparing base (fd84020) to head (548b888). Report is 14 commits behind head on main.

Files	Patch %	Lines
src/main/java/com/shaft/api/RestActions.java	83.33%	0 Missing and 1 partial :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1703 +/- ## ============================================ + Coverage 53.54% 53.95% +0.40% - Complexity 1283 1331 +48 ============================================ Files 111 112 +1 Lines 9945 9998 +53 Branches 959 964 +5 ============================================ + Hits 5325 5394 +69 + Misses 4020 3994 -26 - Partials 600 610 +10 ```

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[KyrillosNageh]

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