use pip for specific python version code example

Example 1: pip install specific version

# To install a specific version of a package using pip:
pip install Package_name==version

# Example:
pip install MySQL_python==1.2.2

Example 2: how to pip install a specific version

# At the time of writing this numpy is in version 1.19.x
# This statement below will install numpy version 1.18.1
python -m pip install numpy==1.18.1