Fix webgoat-lesson-template parent artifact ref

WebGoat 8 latest ([develop](WebGoat@9fdbbf6)) has the following compilation error:

```
Building Maven project at /builds/gitlab-org/security-products/tests/webgoat/webgoat-lessons/webgoat-lesson-template.
[INFO] Scanning for projects...
[ERROR] [ERROR] Some problems were encountered while processing the POMs:
[FATAL] Non-resolvable parent POM for org.owasp.webgoat.lesson:webgoat-lesson-template:[unknown-version]: Could not find artifact org.owasp.webgoat.lesson:webgoat-lessons-parent:pom:8.0-SNAPSHOT and 'parent.relativePath' points at wrong local POM @ line 6, column 13
 @ 
[ERROR] The build could not read 1 project -> [Help 1]
[ERROR]   
[ERROR]   The project org.owasp.webgoat.lesson:webgoat-lesson-template:[unknown-version] (/builds/gitlab-org/security-products/tests/webgoat/webgoat-lessons/webgoat-lesson-template/pom.xml) has 1 error
[ERROR]     Non-resolvable parent POM for org.owasp.webgoat.lesson:webgoat-lesson-template:[unknown-version]: Could not find artifact org.owasp.webgoat.lesson:webgoat-lessons-parent:pom:8.0-SNAPSHOT and 'parent.relativePath' points at wrong local POM @ line 6, column 13 -> [Help 2]
[ERROR] 
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR] 
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/ProjectBuildingException
[ERROR] [Help 2] http://cwiki.apache.org/confluence/display/MAVEN/UnresolvableModelException
Error: Project couldn't be built: exit status 1
```

This is due to an invalid (obsolete) ref in the parent artifact.

Full logs: https://gitlab.com/gitlab-org/security-products/tests/webgoat/-/jobs/322887707

webgoat-lessons/webgoat-lesson-template/pom.xml

@@ -6,7 +6,7 @@
     <parent>
         <groupId>org.owasp.webgoat.lesson</groupId>
         <artifactId>webgoat-lessons-parent</artifactId>
-        <version>8.0-SNAPSHOT</version>
+        <version>v8.0.0-SNAPSHOT</version>
     </parent>
 
-</project>
+</project>