[devhelp] AppData: update project license

[Sébastien Wilmet <swilmet src gnome org>]

commit ff25171187d2a75f3de0b5cea8db6e3d5d437ac3
Author: Sébastien Wilmet <swilmet gnome org>
Date:   Mon Apr 2 06:02:07 2018 +0200

    AppData: update project license
    
    Forgot to update the AppData, see:
    commit 6e0a78bce8be3e9b2a9e4454b9b11f80531a6f91

 data/org.gnome.Devhelp.appdata.xml.in |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/data/org.gnome.Devhelp.appdata.xml.in b/data/org.gnome.Devhelp.appdata.xml.in
index 5203be4..9d7eb1e 100644
--- a/data/org.gnome.Devhelp.appdata.xml.in
+++ b/data/org.gnome.Devhelp.appdata.xml.in
@@ -2,7 +2,7 @@
 <component type="desktop">
   <id>org.gnome.Devhelp.desktop</id>
   <metadata_license>CC0-1.0</metadata_license>
-  <project_license>GPL-2.0+</project_license>
+  <project_license>GPL-3.0+</project_license>
   <name>Devhelp</name>
   <summary>A developer tool for browsing and searching API documentation</summary>
   <description>