build(deps): bump io.undertow:undertow-core

Bumps [io.undertow:undertow-core](https://github.com/undertow-io/undertow) from 2.3.15.Final to 2.3.18.Final.
- [Release notes](https://github.com/undertow-io/undertow/releases)
- [Commits](undertow-io/undertow@2.3.15.Final...2.3.18.Final)

---
updated-dependencies:
- dependency-name: io.undertow:undertow-core
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

build.gradle.kts

@@ -75,7 +75,7 @@ dependencies {
     testImplementation(libs.mockserver.netty)
 
     constraints {
-        implementation("io.undertow:undertow-core:2.3.15.Final") { // keycloak
+        implementation("io.undertow:undertow-core:2.3.18.Final") { // keycloak
             because("https://security.snyk.io/vuln/SNYK-JAVA-IOUNDERTOW-6567186")
         }
         implementation("org.bouncycastle:bcprov-jdk18on:1.78.1") { // keycloak