main/libgit2: upgrade to 1.0.0

Ref https://github.com/libgit2/libgit2/releases/tag/v0.28.5

-usr/lib/libgit2.so.0.28.4
+usr/lib/libgit2.so.0.28.5
 usr/lib/libgit2.so.28

Bump because ABI https://github.com/libgit2/libgit2/releases/tag/v1.0.0

-usr/lib/libgit2.so.0.28.4
-usr/lib/libgit2.so.28
+usr/lib/libgit2.so.1.0
+usr/lib/libgit2.so.1.0.0