cv2.__version__ does not print the full version

Expected behaviour

Getting the version of opencv should allow a user to pip install that same version in a different environment

Actual behaviour

The version number attribute for 4.7.0 was missing the full semantic version

Steps to reproduce

import cv2
cv2.version
'4.7.0'

[5/8] RUN pip install opencv-python==4.7.0:
0.828 ERROR: Could not find a version that satisfies the requirement opencv-python==4.7.0 (from versions: 3.4.0.14, 3.4.10.37, 3.4.11.39, 3.4.11.41, 3.4.11.43, 3.4.11.45, 3.4.13.47, 3.4.15.55, 3.4.16.57, 3.4.16.59, 3.4.17.61, 3.4.17.63, 3.4.18.65, 4.3.0.38, 4.4.0.40, 4.4.0.42, 4.4.0.44, 4.4.0.46, 4.5.1.48, 4.5.3.56, 4.5.4.58, 4.5.4.60, 4.5.5.62, 4.5.5.64, 4.6.0.66, 4.7.0.68, 4.7.0.72, 4.8.0.74, 4.8.0.76, 4.8.1.78, 4.9.0.80, 4.10.0.82, 4.10.0.84)
0.828 ERROR: No matching distribution found for opencv-python==4.7.0

Start by reproducing the reported cv2.version result and compare it with the available opencv-python package versions shown in the issue. Trace how the package version is exposed through cv2 and how the wheel version is published. Done means the reported version can be used to install the corresponding package version.