Bump LibGit2Sharp from 0.30.0 to 0.31.0 (#39)

---
updated-dependencies:
- dependency-name: LibGit2Sharp
  dependency-version: 0.31.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

ApprovalTestTool/ApprovalTestTool.csproj

@@ -8,7 +8,7 @@
     </PropertyGroup>
 
     <ItemGroup>
-        <PackageReference Include="LibGit2Sharp" Version="0.30.0"/>
+        <PackageReference Include="LibGit2Sharp" Version="0.31.0"/>
     </ItemGroup>
 
     <ItemGroup>