Kotlin: Drop support for 1.4.32

We never claimed to support anything < 1.5.0, and compiling with
-language-version 1.4 fails as it's not meant to support sealed classes.

If we build 1.4.32 with -language-version 1.5 using a 2.0 compiler,
then the resulting plugin also fails.

java/kotlin-extractor/kotlin_plugin_versions.py

@@ -24,7 +24,7 @@ def version_string_to_tuple(version):
 # Version number used by CI.
 ci_version = '1.9.0'
 
-many_versions = [ '1.4.32', '1.5.0', '1.5.10', '1.5.20', '1.5.30', '1.6.0', '1.6.20', '1.7.0', '1.7.20', '1.8.0', '1.9.0-Beta', '1.9.20-Beta' ]
+many_versions = [ '1.5.0', '1.5.10', '1.5.20', '1.5.30', '1.6.0', '1.6.20', '1.7.0', '1.7.20', '1.8.0', '1.9.0-Beta', '1.9.20-Beta' ]
 
 many_versions_tuples = [version_string_to_tuple(v) for v in many_versions]