test_ssl.rb: Fix key numbering in test_pqc_sigalg

[junaruga]

I noticed that the rsa-1 is used for certificate (CA) and server in the test/openssl/test_ssl.rb test_pqc_sigalg test, as @ca_key and @ca_cert are created by rsa-1 according to the following logic:

test/openssl/test_ssl.rb

  def setup
...
    @ca_key  = Fixtures.pkey("rsa-1")
    @svr_key = Fixtures.pkey("rsa-2")
    @cli_key = Fixtures.pkey("rsa-3")
...
    @ca_cert  = issue_cert(@ca, @ca_key, 1, @ca_exts, nil, nil)
    @svr_cert = issue_cert(@svr, @svr_key, 2, @ee_exts, @ca_cert, @ca_key)
    @cli_cert = issue_cert(@cli, @cli_key, 3, @ee_exts, @ca_cert, @ca_key)
...
  end

I assume that this may not be intentional. So, I changed the key numbers

---

• Align key numbers with the pattern in test/openssl/utils.rb setup: rsa-1 for
  certificate (CA), rsa-2 for server, rsa-3 for client.
• Use mldsa65-1 for certificate and mldsa65-2 for server.
• Use rsa-2 for server, because rsa-1 is already used for certificate (@ca_key,
  @ca_cert).

Assisted-by: Claude Code