Remove trailing space in GPSValid insertion tag

Winlink Express does include this, and neither should we.

internal/forms/builder.go

@@ -302,6 +302,7 @@ func insertionTagReplacer(m *Manager, tagStart, tagEnd string) func(string) stri
  "UDay": formatDay(now, time.UTC),
 
  "GPS": positionFmt(degreeMinute, nowPos),
+ "GPSValid": validPos,
  "GPS_DECIMAL": positionFmt(decimal, nowPos),
  "GPS_SIGNED_DECIMAL": positionFmt(signedDecimal, nowPos),
  "GridSquare": positionFmt(gridSquare, nowPos),
@@ -311,9 +312,6 @@ func insertionTagReplacer(m *Manager, tagStart, tagEnd string) func(string) stri
  // By reading the embedded javascript, they appear to be signed decimal.
  "GPSLatitude": fmt.Sprintf("%.4f", nowPos.Lat),
  "GPSLongitude": fmt.Sprintf("%.4f", nowPos.Lon),
- // TODO: Why a trailing space here?
- // Some forms also adds a whitespace in their <Var > declaration, so we end up with two trailing spaces..
- "GPSValid": fmt.Sprintf("%s ", validPos),
 
  // TODO (other insertion tags found in Standard Forms):
  // SeqNum