new icon: sfml (original, plain)

* Added sfml icons and updated devicon.json
* Optimized sfml images and changed alt names

---------

Co-authored-by: Alex Canales <49886351+canaleal@users.noreply.github.com>
Co-authored-by: Patrik Wehrli <patrik.wehrli@gmail.com>

Author: 3 people

devicon.json

@@ -12181,6 +12181,30 @@
         "color": "#3b4b72",
         "aliases": []
     },
+    {
+        "name": "sfml",
+        "altnames": [
+            "Simple and Fast Multimedia",
+            "Simple and Fast Multimedia Library"
+        ],
+        "tags": [
+            "graphics",
+            "game",
+            "development",
+            "c++"
+        ],
+        "versions": {
+            "svg": [
+                "original",
+                "plain"
+            ],
+            "font": [
+                "plain"
+            ]
+        },
+        "color": "#8cc445",
+        "aliases": []
+    },
     {
         "name": "shopware",
         "altnames": [],