RE_INSERT_VALUES matches values starts with % and ends with s

[Griiid]

Describe the bug

The regex pattern RE_INSERT_VALUES defined and used in cursors.py is wrong.

RE_INSERT_VALUES = re.compile(
    "".join(
        [
            r"\s*((?:INSERT|REPLACE)\b.+\bVALUES?\s*)",
            r"(\(\s*(?:%s|%\(.+\)s)\s*(?:,\s*(?:%s|%\(.+\)s)\s*)*\))",
            r"(\s*(?:ON DUPLICATE.*)?);?\s*\Z",
        ]
    ),
    re.IGNORECASE | re.DOTALL,
)

%\(.+\)s in the value part: r"(\(\s*(?:%s|%\(.+\)s)\s*(?:,\s*(?:%s|%\(.+\)s)\s*)*\))" allows values starts with % and ends with s.

Theses wrong query text (which you don't want?) will be matched:

INSERT INTO xxx(a, b, c) VALUES (%(xxx)s, NOW(), %(ooo)s)
INSERT INTO xxx(a, b, c) VALUES (%(xxx)s, abc124*(!@*$!@)$&)&$)s)

I think what you want is all %s in values, or all %(xxx)s-liked in values.
However, I don't know why you only want to allow these patterns, since this string-formatting will also works: "NOW(), %(a)s, %(b)s, NOW + INTERVAL 1 MINUTE" % {"a": 100, "b": 3}

Why cant the values part in RE_INSERT_VALUES become: r"(\(.+\))" ?
Developers using function executemany should check whether the args and the query text are match or not.
With r"(\(.+\))" values part, users can use SQL functions, numbers, strings, ... etc in query text, which helps developers a lot.

---

One more thing is: users don't know this regex rule until they meet some issue, you should explain how to use executemany in the document, something like:

`executemany` only support `INSERT INTO` or `REPLACE` statments
The format of VALUES in query text should be all %s or all named string-formatting, for example: `(%s, %s, %s)` or `(%(a)s, %(b)s, %(c)s)`, .
If your query text is not matches the rules above, it will use `execute` function with looping args instead.

To Reproduce

Code

con = MySQLdb.connect(...)
cur = con.cursor()
query_text_1 = """INSERT INTO xxx(a, b, c) VALUES (%(xxx)s, NOW(), %(b)s)"""
query_text_2 = """INSERT INTO xxx(a, b, c) VALUES (NOW(), %(xxx)s, %(b)s)"""
args = {"a": 1, "b": 2}
cur.executemany(con, query_text_1, args) # works
cur.executemany(con, query_text_2, args) # NOT works

Environment

MySQL Server

MySQL 5.7

MySQL Client

• OS (e.g. Windows 10, Ubuntu 20.04): macOS 12.5.1

• Python (e.g. Homebrew Python 3.7.5): python install with pyenv: 3.7, 3.8, 3.10

• Connector/C (e.g. Homebrew mysql-client 8.0.18): mysql-client