Calendar: remove past events

wiki/src/contribute/calendar.mdwn

 [[!meta title="Calendar"]]
 
-* 2017-11-02, 16:00 (Berlin time): CI team meeting
-
-* 2017-11-13:
-   - All feature branches targeting Tails 3.3 should be merged into
-     the `stable` branch by noon, CET. I'm open to make exceptions
-     if you can be online and responsive during that afternoon, but
-     ask me first!
-   - Build and upload Tails 3.3.
-   - Start testing Tails 3.3 during late CET if building the image
-     went smoothly.
-
-* 2017-11-14:
-   - Finish testing Tails 3.3 by the afternoon, CET.
-   - Release Tails 3.3 (bugfix release).
-
 * 2017-12-07, 16:00 (Berlin time): CI team meeting
 
 * 2018-01-04, 16:00 (Berlin time): CI team meeting