Misspecified observable_regex in DiseasystoreEcdcRespiratoryViruses

[RasmusSkytte]

Describe the bug
The observable_regex in DiseasystoreEcdcRespiratoryViruses is misspecified so no observables are listed in the diseaysstore

To Reproduce

ds <- DiseasystoreEcdcRespiratoryViruses$new(target_conn = DBI::dbConnect(RSQLite::SQLite()))

ds$available_observables

Expected behaviour
A clear and concise description of what you expected to happen.

Screenshots
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Provide output from sessionInfo()
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• I have checked that the bug is not already described in open issues

Additional context
The fix should be something like

.observables_regex = r"{^\w+_rates}",