fix: make a fake GOP when video dont have B/P frame

[xiaoyuhen]

fix: make a fake GOP when video dont have B/P frame

Description

some video don't have B/P frame, we should make a fake GOP, then we can play it with streaming

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Please also note any relevant details for your test configuration.

• this video can play normally

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules

[codecov-io]

Codecov Report

Merging #85 into master will increase coverage by 0.16%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master      #85      +/-   ##
==========================================
+ Coverage   50.59%   50.76%   +0.16%     
==========================================
  Files         124      124              
  Lines        1753     1759       +6     
==========================================
+ Hits          887      893       +6     
  Misses        866      866

Impacted Files	Coverage Δ
...s/griffith-mp4/src/mp4/utils/getSamplesInterval.js	95.52% <100%> (+0.44%)	⬆️

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