fix: add Czech to Flask definitions

Author: rtroilo

sketch_map_tool/definitions.py

@@ -224,4 +224,10 @@ def create_literature_reference(element) -> LiteratureReference:
 
 ALL_PAPER_FORMATS = [A0, A1, A2, A3, A4, TABLOID, LETTER]
 
-LANGUAGES = {"en": "English", "de": "Deutsch", "es": "Español", "fr": "Français"}
+LANGUAGES = {
+    "en": "English",
+    "de": "Deutsch",
+    "es": "Español",
+    "fr": "Français",
+    "cs": "Český",
+}