Bump version of jvmdg to 2.0.1

[Nikolay-Sitnikov]

Summary

Updates JVM Downgrader to version 2.0.1, which includes a fix for switch statements testing for instance-of being miscompiled for Java versions 21, 22, and 23 (see unimined/JvmDowngrader#46 for details.)

PR has been tested: without this changed version of GTNHGradle applied, running code like this within a mod would cause a crash on Java 21. With this change, this code runs successfully on Java 21.

Number num = 10;
switch (num) {
    case Integer i -> {
        System.out.println(i);
    }
    case Double d -> {
        System.out.println(d);
    }
    default -> {}
}

Checklist

• I have tested this PR in DevEnv
• I have tested this PR in Fullpack - Should be irrelevant.
• This PR is in compliance with the GTNH AI Policy
• This PR requires another PR in order to merge

[eigenraven]

GTNHLib will also need a matching stub update and then a bump in UpdateableConstants in GTNHGradle