Update dependency python-dotenv to v0.19.2

Author: renovate-bot

requirements.txt

@@ -14,7 +14,7 @@ jinja2==2.11.2; python_version >= "2.7" and python_full_version < "3.0.0" or pyt
 markupsafe==1.1.1; python_version >= "2.7" and python_full_version < "3.0.0" or python_full_version >= "3.5.0"
 protobuf==3.14.0; python_version >= "2.7" and python_full_version < "3.0.0" or python_full_version >= "3.5.0"
 pymysql==1.0.2
-python-dotenv==0.15.0
+python-dotenv==0.19.2
 six==1.15.0; python_version >= "2.7" and python_full_version < "3.0.0" or python_full_version >= "3.5.0"
 sortedcontainers==2.3.0; python_version >= "2.7" and python_full_version < "3.0.0" or python_full_version >= "3.5.0"
 sqlalchemy==1.3.20; python_version >= "2.7" and python_full_version < "3.0.0" or python_full_version >= "3.4.0"