gh-149924 :Increase test coverage for isclose() function with complex numbers

[manoj-km24]

In Lib/test/test_cmath.py, the isclose() function misses certain special test cases for special complex numbers with infinity and Nan. As docs tell:

-inf, inf and NaN behave similarly to the IEEE 754 Standard. 
That is, NaN is not close to anything, even itself. 
inf and -inf are only close to themselves. 

This applies for complex numbers as well (inf + infj , -inf - infj and NaN + NaNj behave in the same way).
This PR adds additional tests for these edge cases.

• Issue: Increase test coverage for isclose() function with edge cases for special complex numbers #149924

[sobolevn]

Please add more cases: for example self.assertIsNotClose(complex(INF, INF), complex(-INF, -INF)) is not covered

[sobolevn]

Suggested change

	self.assertIsClose(complex(INF,INF),complex(INF,INF))
	self.assertIsClose(complex(-INF,-INF),complex(-INF,-INF))
	self.assertIsNotClose(complex(NAN,NAN),complex(NAN,NAN))
	self.assertIsClose(complex(INF, INF), complex(INF, INF))
	self.assertIsClose(complex(-INF, -INF), complex(-INF, -INF))
	self.assertIsNotClose(complex(NAN, NAN), complex(NAN, NAN))

[python-cla-bot]

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• 78011313+ManiSalahmand@users.noreply.github.com

[manoj-km24]

@sobolevn Sorry, I mistakenly polluted this PR. I will open a new one shortly.

[manoj-km24]

The new PR : #149948