chore: isolate dev dependencies into [dev] extra

CONTRIBUTING.rst

@@ -10,7 +10,7 @@ the library off of pip:
 
 .. code-block:: bash
 
-    pip install -U discord-py-interactions
+    pip install -U discord-py-interactions[dev]
 
 Once you have the library installed in Python, you are able to instantiate and run a basic bot
 with a logging level that is set for debugging purposes. This is recommend in order to make it easier

requirements-docs.txt

@@ -0,0 +1,2 @@
+Sphinx==4.1.2
+sphinx-hoverxref==1.0.0

requirements-lint.txt

@@ -0,0 +1,4 @@
+black==21.11b1
+flake8==3.9.2
+isort==5.9.3
+pre-commit==2.16.0

requirements.txt

@@ -1,9 +1,3 @@
 aiohttp==3.7.4.post0
-black==21.11b1
 colorama==0.4.4
-flake8==3.9.2
-isort==5.9.3
-orjson
-pre-commit==2.16.0
-Sphinx==4.1.2
-sphinx-hoverxref==1.0.0
+orjson==3.6.3

setup.py

@@ -12,14 +12,18 @@
 with open(path.join(HERE, PACKAGE_NAME, "base.py"), encoding="utf-8") as fp:
     VERSION = re.search('__version__ = "([^"]+)"', fp.read()).group(1)
 
+
+def read_requirements(filename):
+    with open(filename, "r", encoding="utf-8") as fp:
+        return fp.read().strip().splitlines()
+
+
 extras = {
-    "lint": ["black", "flake8", "isort"],
-    "readthedocs": ["sphinx", "karma-sphinx-theme"],
+    "lint": read_requirements("requirements-lint.txt"),
+    "readthedocs": read_requirements("requirements-docs.txt"),
 }
-extras["lint"] += extras["readthedocs"]
 extras["dev"] = extras["lint"] + extras["readthedocs"]
-
-requirements = open("requirements.txt").read().split("\n")[:-1]
+requirements = read_requirements("requirements.txt")
 
 setup(
     name="discord-py-interactions",