Removed the if condition to make code more concise.

- Instead of checking for `if` condition to populate the `isQuoted` var, we can directly use the boolean result of `!=` relational operator to populate the variable.

- This makes the code concise and more easier to debug and dry-run the while loop.

Sources/Markdown/Parser/BlockDirectiveParser.swift

@@ -414,9 +414,7 @@ struct TrimmedLine {
                 isEscaped = true
             }
             else if isQuoted {
-                if c == "\"" {
-                    isQuoted = false
-                }
+                isQuoted = (c != "\"")
             }
             else if allowQuote,
                c == "\"" {