Update NuGet.org publishing key

Author: nblumhardt

appveyor.yml

@@ -10,7 +10,7 @@ artifacts:
 deploy:
 - provider: NuGet
   api_key:
-    secure: nvZ/z+pMS91b3kG4DgfES5AcmwwGoBYQxr9kp4XiJHj25SAlgdIxFx++1N0lFH2x
+    secure: K3/810hkTO6rd2AEHVkUQAadjGmDREus9k96QHu6hxrA1/wRTuAJemHMKtVVgIvf
   skip_symbols: true
   on:
     branch: /^(master|dev)$/
@@ -20,4 +20,4 @@ deploy:
   artifact: /Serilog.*\.nupkg/
   tag: v$(appveyor_build_version)
   on:
-    branch: master
+    branch: master