cv2.__version__ does not print the full version

[sbhavani]

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