Cannot upgrade timescale with ALTER EXTENSION

[mfundul]

Relevant system information:

• OS: CentOS Linux release 8.3.2011
• postgres (PostgreSQL) 13.3
• Timescale 2.2.0 => Timescale 2.3.0
• Installation method: dnf

Describe the bug
When I execute ALTER EXTENSION timescaledb UPDATE TO "2.3.0"; it fails with:

postgres=# ALTER EXTENSION timescaledb UPDATE TO "2.3.0";
ERROR:  extension "timescaledb" version mismatch: shared library version 2.3.0; SQL version 2.2.0
CONTEXT:  parallel worker

To Reproduce
Steps to reproduce the behavior:

1. Create a dataset (I created 1 compressed hypertable, ~500M rows, ~10GB on disk)
2. Change postgresql.conf as such:

parallel_tuple_cost = 0.001
parallel_setup_cost = 1.0
force_parallel_mode = on

3. Restart the postgresql service
4. Execute ALTER EXTENSION timescaledb UPDATE TO "2.3.0";
5. See error

Expected behavior
Expected the upgrade to work.

Additional context
Setting max_parallel_workers = 0 in postgresql.conf fixes the issue.
For some reason, parallel execution of the upgrade process itself seems to trigger this bug.

A possible workaround could maybe be to inject SET max_parallel_workers = 0; in the upgrade scripts. E.g. in this specific case adding it as the first line of the file /usr/pgsql-13/share/extension/timescaledb--2.2.0--2.3.0.sql fixes the issue.

[mjf]

I can verify that patching the /usr/pgsql-13/share/extension/timescaledb--2.2.[01]--2.3.0.sql files works and the extension gets updated.