`setup.py`: Define version directly

Define the version directly instead of loading from an environment variable and writing to a file.
diff --git a/python/setup.py b/python/setup.py
index 0615f2b..1c07f24 100644
--- a/python/setup.py
+++ b/python/setup.py
@@ -19,44 +19,9 @@
 from datetime import datetime
 from setuptools import setup
 
-
-def _update_version_attr(new_version):
-    for line in fileinput.input('flatbuffers/_version.py', inplace=True):
-        if line.startswith('__version__'):
-            line = re.sub(r'".*"', '"{}"'.format(new_version), line)
-        sys.stdout.write(line)
-
-
-def version():
-    version = os.getenv('VERSION', None)
-    if version:
-        # Most git tags are prefixed with 'v' (example: v1.2.3) this is
-        # never desirable for artifact repositories, so we strip the
-        # leading 'v' if it's present.
-        version = version[1:] if version.startswith('v') else version
-    else:
-        # Default version is an ISO8601 compiliant datetime. PyPI doesn't allow
-        # the colon ':' character in its versions, and time is required to allow
-        # for multiple publications to master in one day. This datetime string
-        # uses the "basic" ISO8601 format for both its date and time components
-        # to avoid issues with the colon character (ISO requires that date and
-        # time components of a date-time string must be uniformly basic or
-        # extended, which is why the date component does not have dashes.
-        #
-        # Publications using datetime versions should only be made from master
-        # to represent the HEAD moving forward.
-        version = datetime.utcnow().strftime('%Y%m%d%H%M%S')
-        print("VERSION environment variable not set, using datetime instead: {}"
-              .format(version))
-
-    _update_version_attr(version)
-
-    return version
-
-
 setup(
     name='flatbuffers',
-    version=version(),
+    version='22.10.25',
     license='Apache 2.0',
     author='FlatBuffers Contributors',
     author_email='me@rwinslow.com',
@@ -81,4 +46,4 @@
         'Documentation': 'https://google.github.io/flatbuffers/',
         'Source': 'https://github.com/google/flatbuffers',
     },
-)
\ No newline at end of file
+)