update sponsor links

Author: jmckenna

en/community/contributors.txt

@@ -25,7 +25,7 @@ Sponsors (Past and Present)
   - OGC service and SLD fixes
   - General MapServer fixes and improvements
 
-`DM Solutions`_
+DM Solutions
   - OGC support (2001-2005)
   - PHP-MapScript implementation and Support
   - MapServer Release Management
@@ -36,7 +36,7 @@ Sponsors (Past and Present)
 `Environment Canada`_
   - :ref:`RFC 13 <rfc13>`: SOS Server support (2006-2007)
 
-`Gateway Geomatics`_
+`GatewayGeo`_
   - MS4W installer for Windows users
   - MapServer user documentation
   - MapServer website maintenance
@@ -73,11 +73,11 @@ Source Code Contributors (Past and Present)
 
 .. _`i-cubed`: http://www.i3.com 
 .. _`Environment Canada`: https://weather.gc.ca/
-.. _`RealGo`: http://www.realgo.com 
+.. _`RealGo`: https://www.realgo.com 
 .. _`DM Solutions`: http://www.dmsolutions.ca/
 .. _`Refractions Research`: http://www.refractions.net/
-.. _`TMC Technologies`: http://www.tmctechnologies.com/
-.. _`Tydac AG`: http://www.tydac.ch/
-.. _`Gateway Geomatics`: https://gatewaygeomatics.com
+.. _`TMC Technologies`: https://www.tmctechnologies.com/
+.. _`Tydac AG`: https://www.tydac.ch/
+.. _`GatewayGeo`: https://gatewaygeomatics.com
 .. _`Compass Informatics`: https://compass.ie/
 .. _`ISRIC World Soil Information`: https://www.isric.org/