Java/JDK 21 fix for regex (incomplete)

[danielnaber]

Attempt to make tests work with JDK 21, had to stop as it's more complicated than just fixing regex in the XML files.

E.g. CatalanSentenceTokenizerTest fails:

java.lang.AssertionError: 
Expected :[Desprèn. , A mi em feia estrany.]
Actual   :[Desprèn. A mi em feia estrany.]
<Click to see difference>


	at org.junit.Assert.fail(Assert.java:89)
	at org.junit.Assert.failNotEquals(Assert.java:835)
	at org.junit.Assert.assertEquals(Assert.java:120)
	at org.junit.Assert.assertEquals(Assert.java:146)
	at org.languagetool.TestTools.testSplit(TestTools.java:84)
	at org.languagetool.tokenizers.ca.CatalanSentenceTokenizerTest.testSplit(CatalanSentenceTokenizerTest.java:125)
	at org.languagetool.tokenizers.ca.CatalanSentenceTokenizerTest.testTokenize(CatalanSentenceTokenizerTest.java:59)

Also PortugueseWordRepeatBeginningRuleTest:

[ERROR] Tests run: 1, Failures: 1, Errors: 0, Skipped: 0, Time elapsed: 1.146 s <<< FAILURE! - in org.languagetool.rules.pt.PortugueseWordRepeatBeginningRuleTest
[ERROR] org.languagetool.rules.pt.PortugueseWordRepeatBeginningRuleTest.testRule  Time elapsed: 1.146 s  <<< FAILURE!
java.lang.AssertionError: expected:<1> but was:<0>
	at org.junit.Assert.fail(Assert.java:89)
	at org.junit.Assert.failNotEquals(Assert.java:835)
	at org.junit.Assert.assertEquals(Assert.java:647)
	at org.junit.Assert.assertEquals(Assert.java:633)
	at org.languagetool.rules.pt.PortugueseWordRepeatBeginningRuleTest.testRule(PortugueseWordRepeatBeginningRuleTest.java:45)

More will probably pop up once these are fixed...