(build) Try to force installation of newer package

Older package versions of Cake.Twitter simply don't work, due to a
change in how Twitter itself works.  This commit attempts to install the
latest Cake.Twitter version that we can use, in a hope to get tweets
working again as part of our releases.

Author: gep13

47dc2ec9-b548-41ac-a2e9-4fd238472b8e.cake

@@ -0,0 +1 @@
+#tool dotnet:?package=GitVersion.Tool&version=5.6.7

recipe.cake

@@ -1,6 +1,7 @@
 #load nuget:?package=Cake.Recipe&version=3.1.1
 #tool dotnet:?package=dotnet-t4&version=2.2.1
 #addin nuget:?package=Cake.Git&version=1.0.0
+#addin nuget:?package=Cake.Twitter&version=1.1.1
 
 Environment.SetVariableNames(githubTokenVariable: "GITTOOLS_GITHUB_TOKEN");