plugins: feature #449 allow fract DPI values when importing PDF (for 2-10)
requested to merge StanislavGrinkov/gimp:feature-449-allow-non-integer-dpi-on-import-2-10 into gimp-2-10
This commit fixes the issue when requested page width/height was not honored because DPI resolution value was constrained to whole integer numbers only.
(was fixed for 2.99, now for 2.10)