dl.espressif.com is now using the same root certificate as github.com.
This commit replaces the previously-used ISRG X1 root certificate
with the DigiCert Root CA certificate.
As a result, even if the certificates are not installed (as it happens
on macOS with python.org installers, if the user forgets to run
'Install Certificates.command'), the download is successful.
Related to https://github.com/espressif/esp-idf/issues/4081
