fix: replace filter by a for loop in getMinMax to prevent the call stack to fill up.

[levaphenyl]

When uploading a time series that is too large, the upload fails with error RangeError: Maximum call stack size exceeded.
This is due to the use of filter(...).map(...) in the getMinMax function, as it fills the call stack with small function calls.
Possibly related to #109

[zekeshearer]

@levaphenyl, could you provide an example dataset that is large enough to fail without this fix? Thanks, Zeke

[daterdots]

Here's a test file with 1M rows
filesdummy-input-length-1e+06.csv.zip

[levaphenyl]

Closing in favor of #117, whose solution is more elegant.