Remove cache=shared option for less database is locked errors

Inspired by mattn/go-sqlite3#209, but we are
not following their advice because `db.SetMaxOpenConns(1)` destroys our
performance because we require the database queries (and updates) to run
in parallel.

This seems to make the `database is locked` errors go away a bit, at
least in local testing

database.go

@@ -13,7 +13,7 @@ import (
 )
 
 func InitDatabase(dbPath string) (*sql.DB, error) {
-	db, err := sql.Open("sqlite3", "file:"+dbPath+"?_journal_mode=WAL&cache=shared&_busy_timeout=50")
+	db, err := sql.Open("sqlite3", "file:"+dbPath+"?_journal_mode=WAL&_busy_timeout=50")
 	if err != nil {
 		return nil, fmt.Errorf("open: %w", err)
 	}