switched to static renderer to save space

[ngupta23]

Related Issue or bug

Time Series tutorial notebooks not rendering on nbviewer. Probably due to size of notebooks (some are over 50MB due to interactive plots)

Describe the changes you've made

Switched to a static png renderer to save space. Size < 10MB on all notebooks now. This is working now

• https://nbviewer.org/github/pycaret/pycaret/blob/ts_notebooks/tutorials/time_series/forecasting/univariate_with_exogeneous_part1.ipynb
• https://nbviewer.org/github/pycaret/pycaret/blob/ts_notebooks/tutorials/time_series/forecasting/univariate_without_exogeneous_part1.ipynb
• https://nbviewer.org/github/pycaret/pycaret/blob/ts_notebooks/tutorials/time_series/forecasting/customizing_experiments.ipynb

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Code style update (formatting, local variables)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Existing tests to pass on GH

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.
• I have added tests that prove my fix is effective or that my feature works.
• New and existing unit tests pass locally with my changes.
• Any dependent changes have been merged and published in downstream modules.