[feature] support tinyint type default convert to int(not str) · Pull Request !9 · openGauss/openGauss-connector-python-psycopg2

**What this PR does / why we need it**:
This PR to support tinyint default convert to int, not str.
**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes #I56S1E

**Special notes for your reviewer**:
1. tinyint default reflect to pg_type int1, oid is 5545。so just put 5545 to typecast_buildin module for int convert。
2. another way to support tinyint convert is use psycopg2.extensions.register_type() to declare it. sample like this:
```import os
import sys
PSYCOPG2_ROOT = '/xxx/openGauss-connector-python-psycopg2/output/'
sys.path.insert(0, PSYCOPG2_ROOT)
import psycopg2
connector_args = {
    'database': 'postgres',
    'user': 'test',
    'password': '******',
    'host': '127.0.0.1',
    'port': '5543'
}

tinyint_type = psycopg2.extensions.new_type((5545,), 'tinyint', lambda s, conn_or_curs: int(s))
psycopg2.extensions.register_type(tinyint_type, None)
def test_connect():
    conn = None
    try:
        conn = psycopg2.connect(**connector_args)
        curs = conn.cursor()
        curs.execute('drop table if exists t1;')
        curs.execute('create table t1(col tinyint);')
        curs.execute('insert into t1 values (%s);', (255,))
        curs.execute('select * from t1;')
        x = curs.fetchone()
        print(type(x[0]), x)
    except Exception as exp:
        print('print error:%s'%(exp))
    finally:
        if conn is not None:
            conn.close()
test_connect()

**Release note**:

```release-note
```
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