added try-catch workaround for SQL.connect when sqlite3 is not available

Author: rongxin-liu

setup.py

@@ -18,5 +18,5 @@
     package_dir={"": "src"},
     packages=["cs50"],
     url="https://github.com/cs50/python-cs50",
-    version="9.2.3"
+    version="9.2.4"
 )

src/cs50/sql.py

@@ -80,10 +80,14 @@ def __init__(self, url, **kwargs):
         def connect(dbapi_connection, connection_record):
 
             # Enable foreign key constraints
-            if type(dbapi_connection) is sqlite3.Connection:  # If back end is sqlite
-                cursor = dbapi_connection.cursor()
-                cursor.execute("PRAGMA foreign_keys=ON")
-                cursor.close()
+            try:
+                if type(dbapi_connection) is sqlite3.Connection:  # If back end is sqlite
+                    cursor = dbapi_connection.cursor()
+                    cursor.execute("PRAGMA foreign_keys=ON")
+                    cursor.close()
+            except:
+                # Temporary fix for missing sqlite3 module on the buildpack stack
+                pass
 
         # Register listener
         sqlalchemy.event.listen(self._engine, "connect", connect)