update example notebooks with pip

[MojammelHossain]

Updated the example notebooks with pip install also added reason in the comment for FileNotFoundError.

[github-actions]

Locust summary

Git references

Initial: 09e3998
Terminal: 32f54a7

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[codecov]

Codecov Report

Merging #585 (32f54a7) into master (09e3998) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #585   +/-   ##
=======================================
  Coverage   89.17%   89.17%           
=======================================
  Files          52       52           
  Lines        3852     3852           
=======================================
  Hits         3435     3435           
  Misses        417      417           

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