db: use Text where length not limited

Fixes sopel-irc#2291

sopel/db.py

@@ -7,7 +7,7 @@
 import traceback
 import typing
 
-from sqlalchemy import Column, create_engine, ForeignKey, Integer, String
+from sqlalchemy import Column, create_engine, ForeignKey, Integer, String, Text
 from sqlalchemy.engine.url import make_url, URL
 from sqlalchemy.exc import OperationalError, SQLAlchemyError
 from sqlalchemy.ext.declarative import declarative_base
@@ -62,26 +62,26 @@ class NickValues(BASE):
     __tablename__ = 'nick_values'
     __table_args__ = MYSQL_TABLE_ARGS
     nick_id = Column(Integer, ForeignKey('nick_ids.nick_id'), primary_key=True)
-    key = Column(String(255), primary_key=True)
-    value = Column(String(255))
+    key = Column(Text, primary_key=True)
+    value = Column(Text)
 
 
 class ChannelValues(BASE):
     """Channel values table SQLAlchemy class."""
     __tablename__ = 'channel_values'
     __table_args__ = MYSQL_TABLE_ARGS
     channel = Column(String(255), primary_key=True)
-    key = Column(String(255), primary_key=True)
-    value = Column(String(255))
+    key = Column(Text, primary_key=True)
+    value = Column(Text)
 
 
 class PluginValues(BASE):
     """Plugin values table SQLAlchemy class."""
     __tablename__ = 'plugin_values'
     __table_args__ = MYSQL_TABLE_ARGS
-    plugin = Column(String(255), primary_key=True)
-    key = Column(String(255), primary_key=True)
-    value = Column(String(255))
+    plugin = Column(Text, primary_key=True)
+    key = Column(Text, primary_key=True)
+    value = Column(Text)
 
 
 class SopelDB: