[gimp-web] Update gimp_versions with GIMP 2.99.6.

[Jehan <jehanp src gnome org>]

commit 0d94c3d5af389b841371a18c0d0446ce84af52ad
Author: Jehan <jehan girinstud io>
Date:   Sat May 8 02:34:54 2021 +0200

    Update gimp_versions with GIMP 2.99.6.

 content/gimp_versions.json | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)
---
diff --git a/content/gimp_versions.json b/content/gimp_versions.json
index 6a0f16a0..8790c208 100644
--- a/content/gimp_versions.json
+++ b/content/gimp_versions.json
@@ -512,6 +512,27 @@
         }
     ],
     "DEVELOPMENT":  [
+        {
+            "version": "2.99.6",
+            "date": "2021-04-26",
+            "source": [
+                {
+                    "filename": "gimp-2.99.6.tar.bz2 ",
+                    "sha512": 
"51ada696693ac51624ba222d1fff54d39bdc72a06de54f7c244b89740b77f7205aab44f1cec90785ca4196cab32f817e7390b4287a30f5024606163f24222961",
+                    "sha256": "8d264b28445a3df2b940f30ee0b89b469255e975e8563b889fd57fb2f58f66a0"
+                }
+            ],
+            "windows": [
+                 {
+                    "date": "2021-05-05",
+                    "filename": "gimp-2.99.6-setup.exe",
+                    "sha512": 
"37cc5bdbe55fe44d4e5b54fc86b64ce7c0f54aa5d70b8093c72af96278982d6eac417956bf46e1df1af9aef1f128109e5415a254ced992644e9a41b2537891b6",
+                    "sha256": "24f46ef167463935e4a320a33bb91cd86a901d26d953b4e0a6eda2aa958117bc",
+                    "min-support": "Windows 7",
+                    "build-id": "org.gimp.GIMP_official"
+                }
+            ]
+        },
         {
             "version": "2.99.4",
             "date": "2020-12-25",