missing pymysql and SQLAlchemy in requirements.txt

When you try install osprofiler in isolated virtual env or separate container, the installation will complete but first time you run osprofiler you will end up with below error:

$ osprofiler trace show --connection-string mysql+pymysql://profiler:password@[fd00:f00c::c0a8:e06]/profiler --html e76f4cfe-75e5-4a9a-af20-bbe1edd7c164
To use this command, install 'SQLAlchemy'
Traceback (most recent call last):
  File "/home/radek/tmp/venv3-osprofiler2/lib64/python3.6/site-packages/osprofiler/drivers/sqlalchemy_driver.py", line 33, in __init__
    from sqlalchemy import create_engine
ModuleNotFoundError: No module named 'sqlalchemy'
Failed to create engine/connection and setup intial database tables
Traceback (most recent call last):
  File "/home/radek/tmp/venv3-osprofiler2/lib64/python3.6/site-packages/osprofiler/drivers/sqlalchemy_driver.py", line 62, in __init__
    self._engine = create_engine(connection_str)
UnboundLocalError: local variable 'create_engine' referenced before assignment
To use this command, you should install 'SQLAlchemy'

The problem is missing:
  +pymysql
  +SQLAlchemy
in requirements.txt file.