Pin NuSpec GitHub link to version tag

Author: dahlbyk

chocolatey/poshgit.nuspec

@@ -27,7 +27,7 @@ Note on performance: displaying file status in the git prompt for a very large r
     <summary>Provides prompt with Git status summary information and tab completion for Git commands, parameters, remotes and branch names.</summary>
     <tags>poshgit posh-git powershell git</tags>
     <projectUrl>https://github.com/dahlbyk/posh-git</projectUrl>
-    <licenseUrl>https://github.com/dahlbyk/posh-git/blob/master/LICENSE.txt</licenseUrl>
+    <licenseUrl>https://github.com/dahlbyk/posh-git/blob/v0.7.0/LICENSE.txt</licenseUrl>
     <requireLicenseAcceptance>false</requireLicenseAcceptance>
     <dependencies>
       <dependency id="git" />