Include `cl-test-more` Dependency for Quicklisp

When installing via Quicklisp, you receive the following when running the `(caveman.skeleton:generate)` command on a fresh install and building the first app skeleton:

```
* (caveman.skeleton.generate #p"~/test")

debugger invoked on a UNDEFINED-FUNCTION in thread
#<THREAD "main thread" RUNNING {1002978CB3}>:
  The function COMMON-LISP-USER::CAVEMAN.SKELETON.GENERATE is undefined.

Type HELP for debugger help, or (SB-EXT:QUIT) to exit from SBCL.

restarts (invokable by number or by possibly-abbreviated name):
  0: [ABORT] Exit debugger, returning to top level.

(SYMBOL-FUNCTION CAVEMAN.SKELETON.GENERATE)
0] ^C

debugger invoked on a SB-SYS:INTERACTIVE-INTERRUPT in thread
#<THREAD "main thread" RUNNING {1002978CB3}>:
  Interactive interrupt at #x7FFFF7269DF8.

Type HELP for debugger help, or (SB-EXT:QUIT) to exit from SBCL.

restarts (invokable by number or by possibly-abbreviated name):
  0: [CONTINUE] Return from SB-UNIX:SIGINT.
  1: [ABORT   ] Exit debugger, returning to top level.

("bogus stack frame")
0[2] 1
```

Therefore, cl-test-more is required to build a project skeleton that can be used by Caveman.