Prepare for v0.25.3 release

Author: ethomson

CHANGES.md

@@ -10,6 +10,16 @@
   - Windows (x86/amd64): <https://ci.appveyor.com/project/libgit2/libgit2sharp>
   - Linux/Mac OS X: <https://travis-ci.org/libgit2/libgit2sharp>
 
+## v0.25.3 - ([diff](https://github.com/libgit2/libgit2sharp/compare/v0.25.2..v0.25.3))
+
+This is a security release fixing a number of possible security issues,
+including hardening validation for submodule validation to help protect
+against CVE 2018-17456, and a number of possible errors found by fuzzing
+the libgit2 native library.
+
+This release includes [libgit2
+v0.27.5](https://github.com/libgit2/libgit2/releases/tag/v0.27.5).
+
 ## v0.25.1 - ([diff](https://github.com/libgit2/libgit2sharp/compare/v0.25..v0.25.1))
 
 This is a security release fixing insufficient validation of submodule

version.json

@@ -1,6 +1,6 @@
 {
   "$schema": "https://raw.githubusercontent.com/AArnott/Nerdbank.GitVersioning/master/src/NerdBank.GitVersioning/version.schema.json",
-  "version": "0.25.2",
+  "version": "0.25.3",
   "publicReleaseRefSpec": [
     "^refs/heads/master$",                  // we release out of master
     "^refs/heads/maint/v\\d+(?:\\.\\d+)?$"  // and maint/vNN branches