pixman: Don't assume even/odd release scheme

"Note, in the past pixman used a numbering scheme with odd minor number
numbers for development versions and even minor number for stable
versions. This is no longer the case, all releases (including this one)
are stable production versions now."

https://www.mail-archive.com/pixman@lists.freedesktop.org/msg04806.html

gvsbuild/projects/pixman.py

@@ -26,7 +26,6 @@ def __init__(self):
  "pixman",
  repository="https://gitlab.freedesktop.org/pixman/pixman",
  version="0.42.2",
- lastversion_even=True,
  archive_url="http://cairographics.org/releases/pixman-{version}.tar.gz",
  hash="ea1480efada2fd948bc75366f7c349e1c96d3297d09a3fe62626e38e234a625e",
  dependencies=["ninja", "meson"],