Version mismatch in springdoc-openapi-tests: sub-modules still reference 2.8.17-SNAPSHOT after version bump to 2.8.18

[ankushsurani]

Description

When cloning the repository and running mvn clean install -DskipTests from
the root, the build fails immediately with:

[FATAL] Non-resolvable parent POM for org.springdoc:springdoc-openapi-tests:2.8.17-SNAPSHOT
Could not find artifact org.springdoc:springdoc-openapi:pom:2.8.17-SNAPSHOT

Root Cause

The root pom.xml was bumped to 2.8.18-SNAPSHOT, but the following modules
were not updated and still reference 2.8.17-SNAPSHOT as their parent version:

• springdoc-openapi-tests/pom.xml
• springdoc-openapi-tests/springdoc-openapi-security-tests/pom.xml
• springdoc-openapi-tests/springdoc-openapi-groovy-tests/pom.xml
• springdoc-openapi-tests/springdoc-openapi-javadoc-tests/pom.xml
• springdoc-openapi-tests/springdoc-openapi-function-webmvc-tests/pom.xml
• springdoc-openapi-tests/springdoc-openapi-function-webflux-tests/pom.xml
• springdoc-openapi-tests/springdoc-openapi-actuator-webflux-tests/pom.xml
• springdoc-openapi-tests/springdoc-openapi-actuator-webmvc-tests/pom.xml
• springdoc-openapi-tests/springdoc-openapi-kotlin-webflux-tests/pom.xml
• springdoc-openapi-tests/springdoc-openapi-kotlin-webmvc-tests/pom.xml
• springdoc-openapi-tests/springdoc-openapi-hateoas-tests/pom.xml
• springdoc-openapi-tests/springdoc-openapi-data-rest-tests/pom.xml

Steps to Reproduce

git clone https://github.com/springdoc/springdoc-openapi.git
cd springdoc-openapi
mvn clean install -DskipTests

Expected Result

Build succeeds.

Actual Result

Build fails — 11 modules cannot resolve their parent POM.

Fix

Update all affected pom.xml files to reference 2.8.18-SNAPSHOT.