Fix TryExec in Linux .desktop files (no quotes)

On my virtual machine GNOME is refusing to display desktop entries
where TryExec is quoted. Indeed the spec only mentions quotes in Exec.

Regression in 5f9fe3e.

resources/net.unvanquished.Unvanquished.desktop

@@ -6,7 +6,7 @@ Icon=unvanquished
 Terminal=false
 Type=Application
 Exec="%1/updater"
-TryExec="%1/updater"
+TryExec=%1/updater
 Categories=Game;ActionGame;StrategyGame;
 # Probably doesn't work since the updater is initially launched, not daemon
 PrefersNonDefaultGPU=true

resources/net.unvanquished.UnvanquishedProtocolHandler.desktop

@@ -5,7 +5,7 @@ NoDisplay=true
 Terminal=false
 Type=Application
 Exec="%1/daemon" -connect %u
-TryExec="%1/daemon"
+TryExec=%1/daemon
 MimeType=x-scheme-handler/unv
 # Unclear if this will work when Breakpad is enabled
 PrefersNonDefaultGPU=true