Fix missing single quote

Jenkinsfile

@@ -14,7 +14,7 @@ pipeline {
             steps {
                 sh "rm -rf '${GOPATH}/src/git.cacert.org' ; mkdir -p '${GOPATH}/src/git.cacert.org'"
                 sh "ln -s '${pwd()}' '${BUILDDIR}'"
-                sh "cd '${BUILDDIR} ; go get -u github.com/golang/dep/cmd/dep && '${GOPATH}/bin/dep' ensure -v"
+                sh "cd '${BUILDDIR}' ; go get -u github.com/golang/dep/cmd/dep && '${GOPATH}/bin/dep' ensure -v"
             }
         }
         stage('Build') {