Input only text string value to search author's name in search results bar

Fixes #70 (closed)

Short description of what this resolves:

The search results bar takes only the text input for searching the author's name in search results and has been disabled for the number and empty value input. Results will be displayed only for test string input to search a particular author's name.

Changes proposed in this pull request:

• written test function to validate the input and detect if a number is present in the string of search results bar or not.
• The search bar will not take number and null value as input
• Validate input function will only return the text string as input value and will not execute for integer and empty string.

Checklist

• My branch is up-to-date with the Upstream develop branch.
• The acceptance, integration, unit tests and linter pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)