Use a name for Beta 1 that deosn't confuse the notarise tool

Author: perdrix52

Installers/macOS/DeepSkyStacker.xml

@@ -1,7 +1,7 @@
 <project>
     <shortName>DeepSkyStacker</shortName>
     <fullName>DeepSkyStacker</fullName>
-    <version>6.1.1 Beta 1</version>
+    <version>6.1.1-Beta-1</version>
     <licenseFile>LICENSE</licenseFile>
     <componentList>
         <component>