Merge pull request #903 from dotnet/fixWarnings

Fix compiler warning

Author: AArnott

src/NerdBank.GitVersioning/VersionFile.cs

@@ -44,7 +44,7 @@ protected VersionFile(GitContext context)
     public bool IsVersionDefined() => this.GetVersion() is object;
 
     /// <inheritdoc cref="GetWorkingCopyVersion(out string?)"/>
-    public VersionOptions? GetWorkingCopyVersion() => this.GetWorkingCopyVersion(out string _);
+    public VersionOptions? GetWorkingCopyVersion() => this.GetWorkingCopyVersion(out _);
 
     /// <summary>
     /// Reads the version file from the working tree and returns the <see cref="VersionOptions"/> deserialized from it.
@@ -213,7 +213,7 @@ protected static VersionOptions TryReadVersionFile(TextReader versionTextContent
                 {
                     if (parentDirectory is object)
                     {
-                        result = this.GetWorkingCopyVersion(parentDirectory, out string _);
+                        result = this.GetWorkingCopyVersion(parentDirectory, out _);
                         if (result is object)
                         {
                             JsonConvert.PopulateObject(