In Zoom, you have the option to set up an open meeting that's available all semester with no end date. First, you'll need to click on the Schedule a New Meeting button from the Zoom tab in Canvas:

Next, scroll down to the Time Zone section. There's an option there to setup a Recurring meeting:

Once you check the Recurring meeting box, you can setup your preferred type of recurrence. If you don't want the meeting to have an end date, select the No Fixed Time option:

When your settings are correct, your Zoom preferences should have Recurring meeting enabled with a No Fixed Time recurrence selected: 

Once you've saved your new meeting preferences, you'll see the meeting labeled as Recurring back on your Zoom tab within Canvas, rather than listing a specific meeting start time: