Rename lstm_prediction.py_tf to lstm_prediction.py

[tinubaby]

Describe your change:

• Add an algorithm?
• Fix a bug or typo in an existing algorithm?
• Documentation change?

Checklist:

• I have read CONTRIBUTING.md.
• This pull request is all my own work -- I have not plagiarized.
• I know that pull requests will not be merged if they fail the automated tests.
• This PR only changes one algorithm file. To ease review, please open separate PRs for separate algorithms.
• All new Python files are placed inside an existing directory.
• All filenames are in all lowercase characters with no spaces or dashes.
• All functions and variable names follow Python naming conventions.
• All function parameters and return values are annotated with Python type hints.
• All functions have doctests that pass the automated testing.
• All new algorithms have a URL in its comments that points to Wikipedia or other similar explanation.
• If this pull request resolves one or more open issues then the commit message contains Fixes: #{$ISSUE_NO}.

[dhruvmanila]

Hey, @tinubaby you need to remove the condition from requirements.txt for tensorflow library so that it will be installed in our tests.

[dhruvmanila]

Also, please collect all your renaming pull requests into one PR. There's no point in keeping them separate, they are minor updates :)

[cclauss]

I believe that this will fail our tests because of #3946

[dhruvmanila]

Closing in favor of #4331