Fixed Brain tumor code

[jaidh01]

Closes: #130

• Title: Fixed Brain Tumor Code
• Your Name: Jai Dhingra
• Idenitfy yourself: GSSOC-extd Contributor, Hacktoberfest

Describe the add-ons or changes you've made 📃

Give a clear description of what have you added or modifications made
In the brainTumorModel.py, a variable name was called without Initializing it.
So, I just Initialized it.

Checklist: ☑️

• My code follows the Contributing Guidelines & Code of Conduct of this project.
• This PR does not contain plagiarized content.
• I have performed a self-review of my own code.
• I have commented my code, particularly wherever it was hard to understand.
• My changes generate no new warnings.

Screenshots 📷

Brain.Tumor.mp4

[github-actions]

Thank you for submitting your pull request! We'll review it as soon as possible. For further communication, join our discord server https://discord.gg/tSqtvHUJzE.

[jaidh01]

Hi @Avdhesh-Varshney , I have done all the changes in this PR and solved all the conflicts.
Hence, this PR is now ready for review.

[jaidh01]

Hi @Zedoman, is it good, or do you think any changes are needed?

[jaidh01]

Hi @Zedoman @Avdhesh-Varshney, thanks for merging the PR.
Just a small request, can you please add the level label as well to this PR.