fix(commands): completion error (#819)

When Lazy commands are searched in command line mode, completion fails
horribly (sometime crashing nvim entirely) when the partial string to
complete contains non-escape characters.
For example, running `:Lazy up[` results in a crash.

The fix is to instruct string.find to perform a literal search, treating
the string to search not as a regular expression.

Author: tzachar

lua/lazy/view/commands.lua

@@ -112,7 +112,7 @@ function M.setup()
 
       ---@param key string
       return vim.tbl_filter(function(key)
-        return key:find(prefix) == 1
+        return key:find(prefix, 1, true) == 1
       end, vim.tbl_keys(M.commands))
     end,
   })