Parser fails to regonize timezones "A" and "P"

[DB-37]

What is happening

For context, some timezones are named with a single letter (A,B,C,D,..,Z) (cf. https://www.timeanddate.com/time/zones/a or https://www.timeanddate.com/time/zones/p)
The parser generally recognizes them correctly as timezones:

In [1]: from dateutil import parser
In [2]: date = parser.parse("Thu Jun 02 11:56:53 B 2011", tzinfos={"B": 2*3600})
In [3]: date
Out[3]: datetime.datetime(2011, 6, 2, 11, 56, 53)
In [4]: date.isoformat()
Out[4]: '2011-06-02T11:56:53+02:00'

However, it seems that timezones A and P are recognized as aliases for AM and PM:

In [3]: parser.parse("Thu Jun 02 12:56:53 A 2011", tzinfos={"A": 3600}).isoformat() # Noon in UTC+1
Out[3]: '2011-06-02T00:56:53' # Midnight in UTC

In [4]: parser.parse("Thu Jun 02 12:56:53 P 2011", tzinfos={"P": -3*3600}).isoformat()
Out[4]: '2011-06-02T12:56:53'

This means that date using 24 hour format in these timezones are broken :

In [5]: parser.parse("Thu Jun 02 13:56:53 A 2011")
---------------------------------------------------------------------------
ParserError                               Traceback (most recent call last)
Cell In[5], line 1
----> 1 parser.parse("Thu Jun 02 13:56:53 A 2011")

File ~/.virtualenvs/tmp-9cee89e9c581522/lib/python3.10/site-packages/dateutil/parser/_parser.py:1368, in parse(timestr, parserinfo, **kwargs)
   1366     return parser(parserinfo).parse(timestr, **kwargs)
   1367 else:
-> 1368     return DEFAULTPARSER.parse(timestr, **kwargs)

File ~/.virtualenvs/tmp-9cee89e9c581522/lib/python3.10/site-packages/dateutil/parser/_parser.py:643, in parser.parse(self, timestr, default, ignoretz, tzinfos, **kwargs)
    640 res, skipped_tokens = self._parse(timestr, **kwargs)
    642 if res is None:
--> 643     raise ParserError("Unknown string format: %s", timestr)
    645 if len(res) == 0:
    646     raise ParserError("String does not contain a date: %s", timestr)

ParserError: Unknown string format: Thu Jun 02 13:56:53 A 2011

What is the result

Dates expressed in A and P timezones are not parsed correctly and can even raise exceptions

What is expected

Dates expressed in A and P timezones are parsed correctly and, if tzinfo is supplied, are offseted correctly