Bump spek_version from 2.0.15 to 2.0.16 in /samples/jvm/spek

Bumps `spek_version` from 2.0.15 to 2.0.16.

Updates `spek-dsl-jvm` from 2.0.15 to 2.0.16
- [Release notes](https://github.com/spekframework/spek/releases)
- [Changelog](https://github.com/spekframework/spek/blob/2.x/docs/breaking-changes.md)
- [Commits](spekframework/spek@2.0.15...2.0.16)

Updates `spek-runner-junit5` from 2.0.15 to 2.0.16
- [Release notes](https://github.com/spekframework/spek/releases)
- [Changelog](https://github.com/spekframework/spek/blob/2.x/docs/breaking-changes.md)
- [Commits](spekframework/spek@2.0.15...2.0.16)

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

samples/jvm/spek/build.gradle

@@ -6,7 +6,7 @@ import org.gradle.api.tasks.testing.logging.TestExceptionFormat
 buildscript {
     ext {
         atrium_version = '0.16.0'
-        spek_version = '2.0.15'
+        spek_version = '2.0.16'
     }
 }