[chore] Fix a few luacheck errors (#8461)

frontend/apps/reader/modules/readerdictionary.lua

@@ -816,8 +816,8 @@ function ReaderDictionary:startSdcv(word, dict_names, fuzzy_search)
     -- because sdcv cannot handle CJK text properly when fuzzy searching (with
     -- Japanese, it returns hundreds of useless results).
     local shouldnt_fuzzy_search = true
-    for _, word in ipairs(words) do
-        if not util.hasCJKChar(word) then
+    for _, w in ipairs(words) do
+        if not util.hasCJKChar(w) then
             shouldnt_fuzzy_search = false
             break
         end

frontend/ui/elements/common_info_menu_table.lua

@@ -1,6 +1,5 @@
 local BD = require("ui/bidi")
 local Device = require("device")
-local Event = require("ui/event")
 local InfoMessage = require("ui/widget/infomessage")
 local UIManager = require("ui/uimanager")
 local Version = require("version")