fix: bump spring-core to Spring Framework 6.2.19 for AntPathMatcher ReDoS fix (#35)

spring-core hardcodes its own spring.version (6.1.20) instead of
inheriting from the Boot BOM like every other module, so it missed
the fix for the AntPathMatcher ReDoS advisory (match/matchStart/
extractUriTemplateVariables vulnerable to a crafted pattern) that
the rest of the reactor already picked up via the Spring Boot 3.5.16
bump. The 6.1.x fix line is enterprise-support-only, so bump
straight to the patched 6.2.19 used everywhere else in this repo.

Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com>

Author: milanrath0d

spring-core/pom.xml

@@ -12,7 +12,7 @@
     </parent>
 
     <properties>
-        <spring.version>6.1.20</spring.version>
+        <spring.version>6.2.19</spring.version>
     </properties>
 
     <dependencies>