tlsv1 alert iso-8859-1 ca error on cert authentication

Steps to reproduce:

1. Install Postgres 17.5 and OpenSsl on Windows 11

2. Run the following commands. Enter `postgres` as common name on client cert creation:

   ```sh
   openssl req -new -x509 -days 365 -nodes -out server.crt -keyout server.key
   openssl req -new -nodes -out client.csr -keyout client.key
   openssl x509 -req -in client.csr -CA server.crt -CAkey server.key -CAcreateserial -out client.crt -days 365
    ```

3. Copy files to server data directory:

    ```sh
    copy server.key "C:\Program Files\PostgreSQL\17\data"
    copy server.crt "C:\Program Files\PostgreSQL\17\data\root.crt"
    copy server.crt "C:\Program Files\PostgreSQL\17\data"

4. Add the following lines to top of `pg_hba.conf`:

       hostssl all postgres ::1/0 cert
       hostssl all postgres 0.0.0.0/0 cert

5. Add the following lines to end of `postgresql.conf`:

       ssl = on
       ssl_ca_file = 'root.crt'
       ssl_cert_file = 'server.crt'
       ssl_key_file = 'server.key'

6. Re-start postgres service

7. Run commands

    ```sh
    set PGSSLCERT=client.crt
    set PGSSLKEY=client.key
    "C:\Program Files\PostgreSQL\17\bin\pg_dump" -f "test.backup" -F c -h localhost -U postgres postgres

 
Observed:

> pg_dump: error: connection to server at "localhost" (::1), port 5432
> failed: SSL error: tlsv1 alert unknown ca

Postgres log contains:

> [unknown] ::1 [unknown] LOG:  could not accept SSL connection:
> certificate verify failed [unknown] ::1 [unknown] DETAIL:  Client
> certificate verification failed at depth 0: self-signed certificate.
>     Failed certificate data (unverified): subject
> "...rju/L=test/O=test/CN=postgres/emailAddress=test@example.com",
> serial number 14465968192346824308, issuer
> "...rju/L=test/O=test/CN=postgres/emailAddress=test@example.com"

Reported also in

https://stackoverflow.com/questions/79657806/why-postgres-17-cert-authentication-fails-in-windows

Andrus.