fix(security): bump contentstack-utils to 1.5.1 to address Spring CVEs

Bumps contentstack-utils-java: 1.3.0 → 1.5.1
Pulls in fixed transitive Spring Framework dependencies resolving:
- CVE-2026-41840 (High) - DoS via Multipart in WebFlux
- CVE-2026-41851 (High) - DoS via Unbounded SpEL Cache
- CVE-2026-41839 (Medium) - Session Fixation in WebFlux
- CVE-2026-41853 (Medium) - HTTP Request Smuggling
- CVE-2026-41854 (Medium) - SSRF
- CVE-2026-41845 (Medium) - XSS via JavaScriptUtils
- CVE-2026-41848 (Medium) - ReDoS via AntPathMatcher

Author: reeshika-h

pom.xml

@@ -36,7 +36,7 @@
         <json-version>20251224</json-version>
         <jacoco-maven-plugin-version>0.8.11</jacoco-maven-plugin-version>
         <maven-release-plugin-version>2.5.3</maven-release-plugin-version>
-        <contentstack-utils-version>1.3.0</contentstack-utils-version>
+        <contentstack-utils-version>1.5.1</contentstack-utils-version>
     </properties>
 
     <!-- Parent POM removed to avoid 403 from Maven Central in CI (Snyk, etc.). -->