Specify compatible releases in `setup.py`

For more information on compatible releases,
see [PEP 440](https://peps.python.org/pep-0440/#compatible-release)
or [pip's requirement specifiers](https://pip.pypa.io/en/stable/reference/requirement-specifiers/).

In general, `requirements.txt` should be used to define a repeatable installation,
such as a development environment or a production environment.
As such, versions of dependencies contained therein should be as specific as possible.

`install_requires` should be used to indicate dependencies necessary to run the package.
As such, versions of dependencies contained therein should be as broad as possible.

See [“install_requires vs requirements files” on python.org](https://packaging.python.org/en/latest/discussions/install-requires-vs-requirements/)
or [“requirements.txt vs setup.py” on stackoverflow](https://stackoverflow.com/a/43659126) for more information.

Closes #355

setup.py

@@ -11,12 +11,6 @@ here = pathlib.Path(__file__).parent.resolve()
 
 long_description = (here / "README.md").read_text(encoding="utf-8")
 
-with open(here / "requirements.txt") as f:
-    requireds = f.read().splitlines()
-
-with open(here / "requirements-gpu.txt") as f:
-    gpu_requireds = f.read().splitlines()
-
 setup(
     name="rembg",
     description="Remove image background",
@@ -42,14 +36,33 @@ setup(
     keywords="remove, background, u2net",
     packages=["rembg"],
     python_requires=">3.7, <3.11",
-    install_requires=requireds,
+    install_requires=[
+        "aiohttp~=3.8.1",
+        "asyncer~=0.0.2",
+        "click~=8.1.3",
+        "fastapi~=0.87.0",
+        "filetype~=1.2.0",
+        "pooch~=1.6.0",
+        "imagehash~=4.3.1",
+        "numpy~=1.23.5",
+        "onnxruntime~=1.13.1",
+        "opencv-python-headless~=4.6.0.66",
+        "pillow~=9.3.0",
+        "pymatting~=1.1.8",
+        "python-multipart~=0.0.5",
+        "scikit-image~=0.19.3",
+        "scipy~=1.9.3",
+        "tqdm~=4.64.1",
+        "uvicorn~=0.20.0",
+        "watchdog~=2.1.9",
+    ],
     entry_points={
         "console_scripts": [
             "rembg=rembg.cli:main",
         ],
     },
     extras_require={
-        "gpu": gpu_requireds,
+        "gpu": ["onnxruntime-gpu~=1.13.1"],
     },
     version=versioneer.get_version(),
     cmdclass=versioneer.get_cmdclass(),