ioam/holoviews: Version 1.8.1

Version 1.8.1 This bugfix release addresses a number of minor issues identified since the 1.8 release: Feature: All enabled plotting extension logos now shown (#1694) Fixes: Updated search ordering when looking for holoviews.rc (#1700) Fixed lower bound inclusivity bug when no upper bound supplied (#1686) Raise SkipRendering error when plotting nested layouts (#1687) Added safety margin for grid axis constraint issue (#1695) Fixed bug when using +framewise (#1685) Fixed handling of Spacer models in sparse grid (#1682) Renamed Bounds to BoundsXY for consistency (#1672) Fixed bokeh log axes with axis lower bound <=0 (#1691) Set default datashader cmap to fire (#1697) Set SpikesPlot color index to None by default (#1671) Documentation fixes (#1662, #1665, #1690, #1692, #1658