Fix flag of Luxembourg to use the correct colors as specified by their legislation:

http://data.legilux.public.lu/eli/etat/leg/memorial/1993/73/fr/pdf

Namely,

PANTONE Red 032 C, https://www.pantone.com/color-finder/Red-032-C
Hex: #EF3340

PANTONE 299 C, https://www.pantone.com/color-finder/299-C
Hex: #00A3E0

These changes should be contributed back here: https://commons.wikimedia.org/wiki/File:Flag_of_Luxembourg.svg

scripts/flags.json

@@ -705,8 +705,11 @@
 		"ts-using": "2018-08-31 08:41:28 +0100"
 	},
 	"lu": {
-		"wiki-source": "File:<TODO>",
-		"ts-using": "2020-06-30 18:52:59 +0530"
+		"wiki-source": "File:Flag_of_Luxembourg.svg",
+		"sources": [
+			"http://data.legilux.public.lu/eli/etat/leg/memorial/1993/73/fr/pdf"
+		],
+		"ts-using": "2021-04-26T15:10:13Z"
 	},
 	"lv": {
 		"wiki-source": "File:<TODO>",

svg/lu.svg

@@ -1,5 +1 @@
-<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 1000 600">
-<rect width="1000" height="300" y="300" fill="#00a1de"/>
-<rect width="1000" height="300" fill="#ed2939"/>
-<rect width="1000" height="200" y="200" fill="#fff"/>
-</svg>
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 10 6"><path fill="#00A3E0" d="M0 3h10v3H0z"/><path fill="#EF3340" d="M0 0h10v3H0z"/><path fill="#fff" d="M0 2h10v2H0z"/></svg>