go.sum file appears to be out-of-date

[jleveque]

After building the package, git status indicates there are changes to go.sum:

diff --git a/go.sum b/go.sum
index 77b875b..4f0831d 100644
--- a/go.sum
+++ b/go.sum
@@ -35,6 +35,7 @@ github.com/golang/protobuf v1.4.0-rc.1.0.20200221234624-67d41d38c208/go.mod h1:x
 github.com/golang/protobuf v1.4.0-rc.2/go.mod h1:LlEzMj4AhA7rCAGe4KMBDvJI+AwstrUpVNzEA03Pprs=
 github.com/golang/protobuf v1.4.0-rc.4 h1:+EOh4OY6tjM6ZueeUKinl1f0U2820HzQOuf1iqMnsks=
 github.com/golang/protobuf v1.4.0-rc.4/go.mod h1:WU3c8KckQ9AFe+yFwt9sWVRKCVIyN9cPHBJSNnbL67w=
+github.com/golang/protobuf v1.4.0-rc.4.0.20200313231945-b860323f09d0 h1:aRz0NBceriICVtjhCgKkDvl+RudKu1CT6h0ZvUTrNfE=
 github.com/golang/protobuf v1.4.0-rc.4.0.20200313231945-b860323f09d0/go.mod h1:WU3c8KckQ9AFe+yFwt9sWVRKCVIyN9cPHBJSNnbL67w=
 github.com/google/go-cmp v0.2.0/go.mod h1:oXzfMopK8JAjlY9xF4vHSVASa0yLyX7SntLO5aqRK0M=
 github.com/google/go-cmp v0.3.0/go.mod h1:8QqcDgzrUqlUb/G2PQTWiueGozuR1884gddMywk6iLU=
@@ -121,6 +122,7 @@ google.golang.org/protobuf v0.0.0-20200228230310-ab0ca4ff8a60/go.mod h1:cfTl7dwQ
 google.golang.org/protobuf v1.20.1-0.20200309200217-e05f789c0967/go.mod h1:A+miEFZTKqfCUM6K7xSMQL9OKL/b6hQv+e19PK+JZNE=
 google.golang.org/protobuf v1.20.1 h1:ESRXHgpUBG5D2I5mmsQIyYxB/tQIZfSZ8wLyFDf/N/U=
 google.golang.org/protobuf v1.20.1/go.mod h1:KqelGeouBkcbcuB3HCk4/YH2tmNLk6YSWA5LIWeI/lY=
+google.golang.org/protobuf v1.21.0 h1:qdOKuR/EIArgaWNjetjgTzgVTAZ+S/WXVrq9HW9zimw=
 google.golang.org/protobuf v1.21.0/go.mod h1:47Nbq4nVaFHyn7ilMalzfO3qCViNmqZ2kzikPIcrTAo=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/fsnotify.v1 v1.4.7/go.mod h1:Tz8NjZHkW78fSQdbUxIjBTcgA1z1m8ZHf0WmKUhAMys=

It appears as though the file needs to be updated to reflect this.