feat : use --no-cache-dir flag to pip in dockerfiles to save space

[Rajpratik71]

Checklist

• I have followed the Contributor Guidelines.
• The code has been thoroughly tested in my local development environment with flake8 and pylint.
• The code is Python 3 compatible.
• The code follows the PEP8 styling guidelines with 4 spaces indentation.
• This Pull Request relates to only one issue or only one feature
• I have referenced the corresponding issue number in my commit message
• I have added the relevant documentation.
• My branch is up-to-date with the Upstream master branch.

Changes proposed in this pull request

using the "--no-cache-dir" flag in pip install, make sure downloaded packages by pip don't cache on the system. This is a best practice that makes sure to fetch from a repo instead of using a local cached one. Further, in the case of Docker Containers, by restricting caching, we can reduce image size. In terms of stats, it depends upon the number of python packages multiplied by their respective size. e.g for heavy packages with a lot of dependencies it reduces a lot by don't cache pip packages.

Further, more detailed information can be found at

https://medium.com/sciforce/strategies-of-docker-images-optimization-2ca9cc5719b6

Your development environment

• OS: Microsoft Windows 10 Pro
• OS Version: 10.0.19041 Build 19041
• Python Version: Python 3.9.5