RFR: 7903928: update build.gradle to use JDK 23 [v2]

[Athijegannathan Sundararajan]

On Tue, 21 Jan 2025 19:03:52 GMT, Chen Liang <liach at openjdk.org> wrote:

>> README.md line 17:
>> 
>>> 15: ### Building
>>> 16: 
>>> 17: `jextract` depends on the [C libclang API](https://clang.llvm.org/doxygen/group__CINDEX.html). To build the jextract sources, the easiest option is to download LLVM binaries for your platform, which can be found [here](https://releases.llvm.org/download.html) (version 13.0.0 is recommended). Both the `jextract` tool and the bindings it generates depend heavily on the [Foreign Function & Memory API](https://openjdk.java.net/jeps/454), so a suitable [jdk 22+ distribution](https://jdk.java.net/23/) is also required.
>> 
>> This is the only change that wasn't based on review comments, I thought the download page should point to JDK 23
>
> The nominal text should refer to 23, now that gradle passes `--release 23` which is not supported by javac for 22.

Yes, the jextract generated code uses JDK 23 specific API and hence jextract tests fail when jextract repo is built with JDK 22.  

We should stick using/mentioning JDK 23+ everywhere in the "master" branch.

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PR Review Comment: https://git.openjdk.org/jextract/pull/275#discussion_r1924692840