Icons: Fix copyright text line

.icons/app.png.license

@@ -1,3 +1,3 @@
 SPDX-License-Identifier: CC-BY-3.0
-SPDX-License-CopyrightText: delapouite
+SPDX-FileCopyrightText: delapouite
 Original file from https://game-icons.net/1x1/delapouite/keyboard.html

.icons/board.png.license

@@ -1,3 +1,3 @@
 SPDX-License-Identifier: CC-BY-3.0
-SPDX-License-CopyrightText: lorc
+SPDX-FileCopyrightText: lorc
 Original file from https://game-icons.net/1x1/lorc/circuitry.html

.icons/rebuild.py

@@ -20,5 +20,5 @@
     with open(outname + ".license", "w") as licensefile:
         # String is split up because reuse tools would otherwise think this applies here
         print("SPDX-License" + "-Identifier: CC-BY-3.0", file=licensefile)
-        print(f"SPDX-License-CopyrightText: {author}", file=licensefile)
+        print("SPDX-" + f"FileCopyrightText: {author}", file=licensefile)
         print(f"Original file from https://game-icons.net/1x1/{author}/{iconname}.html", file=licensefile)