BF: Remove unecessary float call from movie stim

[TEParsons]

No description provided.

[codecov]

Codecov Report

Merging #3680 (50334df) into release (2a5c02e) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff            @@
##           release    #3680   +/-   ##
========================================
  Coverage    43.24%   43.24%           
========================================
  Files          267      267           
  Lines        52800    52800           
  Branches      9108     9108           
========================================
  Hits         22832    22832           
  Misses       27648    27648           
  Partials      2320     2320           

Impacted Files	Coverage Δ
psychopy/visual/movie3.py	60.90% <100.00%> (ø)

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[coveralls]

Coverage remained the same at 47.076% when pulling 50334df on TEParsons:_movieStimTex into 2a5c02e on psychopy:release.