adjust: default ver to 0.1-dev

this is because when a ver is bumped for release, it's nice to append
-dev after while working on the next release.

So when v0.1 is released, I change the version to v0.2-dev so I know
that's the release I'm working on.

metadata/game_metadata.txt

@@ -2,7 +2,7 @@ devid=myitchusername
 devtitle=My Name
 gameid=my-game-title
 gametitle=My Game Title
-version=0.1
+version=0.1-dev
 icon=metadata/icon.png
 
 # === Flags available at all licensing tiers ===