binning max range of scalar input off by one

[cyrush]

@jfavre noticed strange binning extents, namely that his scalar range max was off by one (too high)

This is the source of the issue:

https://github.com/Alpine-DAV/ascent/blob/deef65e39f3b2792a40281439c4f614488349c0b/src/ascent/runtimes/expressions/ascent_expression_filters.cpp#L2865

We need to either use some small epsilon, or handle otherwise with a special case during the binning home-finding process.