Fix bug in Tensor equal check

[astralcai]

Fixes bug where qml.equal incorrectly returns True when a Tensor is not equal with another non-Tensor observable.

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[astralcai]

[sc-66438]

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 99.67%. Comparing base (ab8b6d5) to head (f8d6db9). Report is 2 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #5877 +/- ## ========================================== - Coverage 99.68% 99.67% -0.01% ========================================== Files 421 421 Lines 40499 40272 -227 ========================================== - Hits 40370 40142 -228 - Misses 129 130 +1 ```

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