Fix http:// URLs that should use https://

[EmilHvitfeldt]

Summary

Several URLs in the repository use http:// instead of https://.

Internal Link (should be fixed)

File	Line	Current URL
packages/index.qmd	106	http://spatialsample.tidymodels.org/

External Links (may need verification)

File	Line	URL	Notes
books/tidytext/index.qmd	16	http://amzn.to/...	Affiliate link
books/tidytext/index.qmd	16	http://www.jdoqocy.com/...	Affiliate link
learn/work/bayes-opt/index.qmd	52	http://www.gaussianprocess.org/gpml/	Academic resource
start/resampling/index.qmd	62	http://www.biomedcentral.com/...	Journal link
learn/develop/broom/index.qmd	310	http://r-pkgs.had.co.nz/man.html	R-pkgs 1st edition
learn/models/parsnip-predictions/index.qmd	175	http://h2o-release.s3.amazonaws.com/...	H2O package repo

Proposed Fix

1. Change http://spatialsample.tidymodels.org/ to https://spatialsample.tidymodels.org/
2. Verify which external links support https and update accordingly