LibGit2Sharp v0.25.2

This release includes all the changes from the previous v0.25.1 release, and correctly updates the version number to v0.25.2.

The prior release, v0.25.1, would incorrectly claim that it was an v0.25.0 prerelease when queried for its version.
v0.25.1 was not available as a NuGet package for this reason.

There are no changes from v0.25.1 other than the version number update.