Kotlin: Add support for 2.0.20

Author: igfoo

docs/codeql/reusables/supported-versions-compilers.rst

@@ -20,7 +20,7 @@
    Java,"Java 7 to 22 [5]_","javac (OpenJDK and Oracle JDK),
 
    Eclipse compiler for Java (ECJ) [6]_",``.java``
-   Kotlin,"Kotlin 1.5.0 to 2.1.0\ *x*","kotlinc",``.kt``
+   Kotlin,"Kotlin 1.5.0 to 2.1.20\ *x*","kotlinc",``.kt``
    JavaScript,ECMAScript 2022 or lower,Not applicable,"``.js``, ``.jsx``, ``.mjs``, ``.es``, ``.es6``, ``.htm``, ``.html``, ``.xhtm``, ``.xhtml``, ``.vue``, ``.hbs``, ``.ejs``, ``.njk``, ``.json``, ``.yaml``, ``.yml``, ``.raml``, ``.xml`` [7]_"
    Python [8]_,"2.7, 3.5, 3.6, 3.7, 3.8, 3.9, 3.10, 3.11, 3.12, 3.13",Not applicable,``.py``
    Ruby [9]_,"up to 3.3",Not applicable,"``.rb``, ``.erb``, ``.gemspec``, ``Gemfile``"

java/ql/integration-tests/kotlin/all-platforms/diagnostics/kotlin-version-too-new/diagnostics.expected

@@ -1,5 +1,5 @@
 {
-  "markdownMessage": "The Kotlin version installed (`999.999.999`) is too recent for this version of CodeQL. Install a version lower than 2.1.10.",
+  "markdownMessage": "The Kotlin version installed (`999.999.999`) is too recent for this version of CodeQL. Install a version lower than 2.1.30.",
   "severity": "error",
   "source": {
     "extractorName": "java",