Track dates of English school holidays

Fixes #168

update.py

@@ -21,6 +21,7 @@ import agenda.mail
 import agenda.thespacedevs
 import agenda.types
 import agenda.uk_holiday
+import agenda.uk_school_holiday
 from agenda.event import Event
 from agenda.types import StrDict
 from web_view import app
@@ -37,6 +38,17 @@ async def update_bank_holidays(config: flask.config.Config) -> None:
     print(f"took {time_taken:.1f} seconds")
 
 
+async def update_school_holidays(config: flask.config.Config) -> None:
+    """Update cached copy of Bristol school holidays."""
+    t0 = time()
+    events = await agenda.uk_school_holiday.get_holiday_list(config["DATA_DIR"])
+    time_taken = time() - t0
+    if not sys.stdin.isatty():
+        return
+    print(len(events), "school holidays in list")
+    print(f"took {time_taken:.1f} seconds")
+
+
 async def update_bristol_bins(config: flask.config.Config) -> None:
     """Update waste schedule from Bristol City Council."""
     t0 = time()
@@ -476,6 +488,7 @@ def main() -> None:
     with app.app_context():
         if hour % 3 == 0:
             asyncio.run(update_bank_holidays(app.config))
+            asyncio.run(update_school_holidays(app.config))
             asyncio.run(update_bristol_bins(app.config))
             update_gwr_advance_ticket_date(app.config)
             # TODO: debug why update gandi fails