[Tests] Remove slimit dependency

The changes to the minify script mean we no longer require slimit.

appveyor.yml

@@ -32,7 +32,6 @@ install:
   - if not defined TOXENV (
     pip install
     -rrequirements.txt
-    slimit
     pygame
     bbfreeze
     pefile

pyproject.toml

@@ -2,7 +2,6 @@
 requires = [
     "setuptools",
     "wheel",
-    "slimit",
 ]
 
 [tool.black]

tox.ini

@@ -18,7 +18,6 @@ sitepackages = True
 deps =
     {[base]deps}
     -rrequirements-tests.txt
-    slimit
 whitelist_externals = pytest
 
 [pytest]
@@ -83,7 +82,6 @@ commands = {[testenv:pydef]commands}
 passenv = HOMEPATH SSH_AUTH_SOCK
 deps =
     pre-commit
-    slimit
 commands =
     pre-commit run --all-files
 
@@ -168,7 +166,6 @@ commands =
 sitepackages = False
 changedir = docs
 deps =
-    slimit
     -rrequirements-docs.txt
 
 [testenv:docs]