Fix IDE integration for Spek unit tests.
Fix IDE integration for Spek unit tests.

See https://github.com/spekframework/spek/issues/278.

Also remove unnecessary exclusion of JUnit platform dependencies - the
Spek JUnit platform engine no longer references anything from JUnit
directly.

charleskorn/batect,charleskorn/batect,charleskorn/batect,charleskorn/batect,charleskorn/batect