GH-131 - Update to Logback 1.5.21.

Author: odrotbohm

pom.xml

@@ -48,7 +48,7 @@
 		<assertj.version>3.27.6</assertj.version>
 		<errorprone.version>2.42.0</errorprone.version>
 		<junit.version>6.0.1</junit.version>
-		<logback.version>1.5.19</logback.version>
+		<logback.version>1.5.21</logback.version>
 		<mockito.version>5.20.0</mockito.version>
 		<nullaway.version>0.12.10</nullaway.version>
 		<spring.version>7.0.0-RC1</spring.version>