Connecting Power BI to PostreSQL managed by Heroku - certificate issue P7B

Hello,

I need to build a direct query connection to PostreSQL db managed by Heroku. The error I get is:

"Unable to connect. Details: An error happened while reading data from the provider: The remote certificate is invalid according to the validation procedure." 

I have received the attached certificates from my IT. 

These work on ODBC connection, therefore we know they are ok. However, we do not want to work with ODBC because it does not have the direct query function. We assume that  that the connection doesn’t work since the provided certificates only work when we can also change the following settings:

sslmode=Require;Trust Server Certificate=true

Since this is not possible in PowerBi we will need a P7B version of the certificate which should not need these properties.
We tried to generate the P7B file based on the files above, but we did not succeed. To our knowledge it is not possible to obtain P7B format directly from Heroku. Can you recommend how to obtain working P7B format or any feasible workaround for this issue?

Thank you!

Lena