Before this patch, the `rustls::RootCertStore::add` method was used
to add all the root certificates found by `rustls_native_certs` crate.
This is a problem when an ancient or invalid certificate is present
in the native root store. `rustls` documentation says the following:
> This is suitable for a small set of root certificates that
> are expected to parse successfully. For large collections of
> roots (for example from a system store) it is expected that
> some of them might not be valid according to the rules `rustls`
> implements. As long as a relatively limited number of certificates
> are affected, this should not be a cause for concern. Use
> `RootCertStore::add_parsable_certificates` in order to add as many
> valid roots as possible and to understand how many certificates have
> been diagnosed as malformed.
With this patch, `RootCertStore::add_parsable_certificates` is used
instead for maximal compability with system store.
> Parse the given DER-encoded certificates and add all that can be
> parsed in a best-effort fashion.
>
> This is because large collections of root certificates often include
> ancient or syntactically invalid certificates.
Benoît CORTIER