Prepare release 4.5.0

Bump version.props from 4.2.0 to 4.5.0, covering all unreleased
additions since 4.2.0:

4.3.0: head, iteri, find, tryFindAsync, tail
4.4.0: findAsync, existsAsync, forallAsync
4.5.0: last, item, tryItem

RELEASE_NOTES.md already contains all three version sections.

Co-authored-by: Copilot <[email protected]>

Author: github-actions[bot]

version.props

@@ -1,5 +1,5 @@
 <Project>
   <PropertyGroup>
-    <Version>4.2.0</Version>
+    <Version>4.5.0</Version>
   </PropertyGroup>
 </Project>