Add the optional rsa dependency to pymysql

This dependency is required to allow compatibility with MySQL instances that enforce specific authentication protocols. This is often the case with managed databases for some public cloud providers.
PyMySQL documentation: https://pymysql.readthedocs.io/en/latest/user/installation.html

requirements.in

@@ -11,7 +11,7 @@ passlib==1.7.4
 bcrypt==4.0.1
 itsdangerous==1.1.0
 requests==2.28.1
-PyMySQL==0.9.3
+PyMySQL[rsa]==0.9.3
 gunicorn==20.1.0
 dataset==1.3.1
 cmarkgfm==2022.10.27

requirements.txt

@@ -29,6 +29,7 @@ certifi==2022.12.7
 cffi==1.15.0
     # via
     #   cmarkgfm
+    #   cryptography
     #   pybluemonday
 charset-normalizer==2.0.12
     # via requests
@@ -36,6 +37,8 @@ click==7.1.2
     # via flask
 cmarkgfm==2022.10.27
     # via -r requirements.in
+cryptography==40.0.2
+    # via pymysql
 dataset==1.3.1
     # via -r requirements.in
 docutils==0.15.2
@@ -117,7 +120,7 @@ pycparser==2.20
     # via cffi
 pydantic==1.6.2
     # via -r requirements.in
-pymysql==0.9.3
+pymysql[rsa]==0.9.3
     # via -r requirements.in
 pyrsistent==0.17.3
     # via jsonschema