Added predict_proba function in Logistic Regression

[rohit-khoiwal]

1. Added a function that gives a class probability for the given input.
   @patel-zeel @karm-patel

[patel-zeel]

LGTM

[coveralls]

Pull Request Test Coverage Report for Build 2467609742

• 4 of 10 (40.0%) changed or added relevant lines in 1 file are covered.
• 2 unchanged lines in 1 file lost coverage.
• Overall coverage increased (+0.01%) to 12.763%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
probml_utils/LogisticRegression.py	4	10	40.0%

Files with Coverage Reduction	New Missed Lines	%
probml_utils/LogisticRegression.py	2	66.67%

Totals
Change from base Build 2466041441:	0.01%
Covered Lines:	504
Relevant Lines:	3949

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💛 - Coveralls