Added change string functionality in Typing Speed Calculator

[Anurag-Gour]

Fixes Issue🛠️

Closes #779

Description👨‍💻

This PR includes addition of a feature in typing speed calculator.

This update makes the typing speed calculator more engaging. Now, when someone types the shown phrase perfectly, with no mistakes, the calculator does two things.

1. First, it shows how fast they typed.
2. Then, it automatically gives them a new phrase to type, clearing the previous attempt at the same time.

This way, people can keep practicing their typing speed.

Type of change📄

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

How this has been tested✅

1. Tested by running code in local machine.
2. Checked that every time new string is assigned.
3. New code doesn't affect any previous code functionality.

Checklist✅

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have added demonstration in the form of GIF/video file
• I am an Open Source Contributor

Screenshots/GIF📷

Untitled1.mp4

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[github-actions]

Hey @Anurag-Gour, Welcome to the project CalcDiverse! 🎊
Thanks for your contribution! Your effort makes this project better. Keep it up! 🙌
Please wait for the PR to be reviewed. Happy Coding!! ✨

[Rakesh9100]

Congrats on getting your PR merged to the repo under GSSOC 2k24 🥳 @Anurag-Gour