[TIMEPIX] Fix types of notebook arguments

Description

When adding Timepix to the update_config script, we noticed some slight type inconsistencies leading to the script not properly working.

1. Changed default value of clustering_epsilon to 2.0 to reflect its float type.
2. Saving threshold_tot as int16 in files to reflect its int type.

Only 1) has been hotfixed on live to make the update script work properly, 2) is only a minor change in data type and can be done later.

How Has This Been Tested?

Default Timepix notebook arguments

Types of changes

• Bug fix (non-breaking change which fixes an issue)

Reviewers

@ahmedk @bjoerns