cli/command/volume TestUpdateCmd: adjust for older error messages

The error-message changed in newer versions, and no longer includes
"exactly".

This patch adjusts the test in the meantime.

    59.13 === FAIL: cli/command/volume TestUpdateCmd (0.00s)
    59.13     update_test.go:21: assertion failed: expected error to contain "requires 1 argument", got "\"update\" requires exactly 1 argument.\nSee 'update --help'.\n\nUsage:  update [OPTIONS] [VOLUME] [flags]\n\nUpdate a volume (cluster volumes only)"

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

cli/command/volume/update_test.go

@@ -18,5 +18,5 @@ func TestUpdateCmd(t *testing.T) {
 
 	err := cmd.Execute()
 
-	assert.ErrorContains(t, err, "requires 1 argument")
+	assert.ErrorContains(t, err, "requires exactly 1 argument")
 }