The SELECT 1 statement does not work on oracle for _check_database checks

[saltlightscript]

Describe the bug
The SELECT 1 statement does not work on oracle

To Reproduce
Steps to reproduce the behavior:

1. Setup an oracle DB in settings.py
2. setup watchman as described in installation instructions
3. Hit the /watchman endpoint or the watchman/dashboard
4. See error

Expected behavior
The checks for the oracle db should pass as it is online

The above exception was the direct cause of the following exception:

Screenshots
If applicable, add screenshots to help explain your problem.

Desktop (please complete the following information):

• OS: [Windows]
• Python version: [3.10]
• Django-watchman version [1.3.0]

Additional context
Traceback points to
Traceback (most recent call last):
File "C:\Users\mdovel\projects\python\inbranch_bdd\lib\site-packages\watchman\decorators.py", line 29, in wrapped
response = func(*args, **kwargs)
File "C:\Users\mdovel\projects\python\inbranch_bdd\lib\site-packages\watchman\checks.py", line 43, in _check_database
cursor.execute("SELECT 1")

Oracle response when trying to run SELECT 1 without a table is
ORA-00923: FROM keyword not found where expected
00923. 00000 - "FROM keyword not found where expected"
*Cause:
*Action:
Error at Line: 1 Column: 8

[luzfcb]

One possible solution is to use the Oracle dummy table, the DUAL table, which, according to the documentation, appears to be well-suited for this purpose.

https://docs.oracle.com/en/database/oracle/oracle-database/21/sqlrf/Selecting-from-the-DUAL-Table.html

That is, when the configured Django's database engine is Oracle (django.db.backends.oracle), the query should be changed to SELECT 1 FROM DUAL.

Oracle Help Center

SQL Language Reference