internal/scan: remove extra dot in a comment

Change-Id: I70cf7c23106578e40c3e344d21f5bf55869e219f
Reviewed-on: https://go-review.googlesource.com/c/vuln/+/559538
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Run-TryBot: Zvonimir Pavlinovic <zpavlinovic@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Maceo Thompson <maceothompson@google.com>

internal/scan/text.go

@@ -135,7 +135,7 @@ func (h *TextHandler) Config(config *govulncheck.Config) error {
 	return h.err
 }
 
-// Progress writes progress updates during govulncheck execution..
+// Progress writes progress updates during govulncheck execution.
 func (h *TextHandler) Progress(progress *govulncheck.Progress) error {
 	h.print(progress.Message, "\n\n")
 	return h.err