pass: trim pass show output

As of 8446a40, pass show will include a newline when showing a password.
This causes the pass helper here to reliably fail to initialize since a
password doesn't round-trip.

Before making this change, the pass test would fail if the installed
password-store version was v1.7.1+, and after this change it passes
again.

Fixes #107

Signed-off-by: Euan Kemp <euank@euank.com>

pass/pass_linux.go

@@ -58,7 +58,8 @@ func runPass(stdin string, args ...string) (string, error) {
 		return "", fmt.Errorf("%s: %s", err, stderr.String())
 	}
 
-	return stdout.String(), nil
+	// trim newlines; pass v1.7.1+ includes a newline at the end of `show` output
+	return strings.TrimRight(stdout.String(), "\n\r"), nil
 }
 
 // Pass handles secrets using Linux secret-service as a store.