Add support for disabling PQ key exchanges to avoid TLS failures

[olii]

Bug Description

In Readme there is an example how to connect to the AlloyDB instance using SOCKS5 proxy:

ALL_PROXY=socks5://localhost:8000 \
HTTPS_PROXY=socks5://localhost:8000 \
    ./alloydb-auth-proxy <INSTANCE_URI>

The above command works in version 1.11.0 but it fails in the 1.11.1 and 1.11.2.

Looking in the commitlog I think that the update to golang 1.23 broke it.

Example code (or command)

No response

Stacktrace

ALL_PROXY=socks5://<proxy_url>:1080 alloydb-auth-proxy --auto-iam-authn "<instance_string>" --run-connection-test
2024/10/11 17:08:33 Authorizing with Application Default Credentials
2024/10/11 17:08:33 [<redacted>] Listening on 127.0.0.1:5432
2024/10/11 17:08:33 The proxy has started successfully and is ready for new connections!
2024/10/11 17:08:33 Connection test started
2024/10/11 17:08:33 Connection test failed
2024/10/11 17:08:33 The proxy has encountered a terminal error: Dial error: handshake failed (instance URI = "<instance_string>"): EOF

### Steps to reproduce?

1. Run the instance of Alloydb in a private VCP
2. Run a socks5 proxy in kubernets with access to the VCP
3. Run the alloydb-auth-proxy with ALL_PROXY set to the socks5 proxy created in step 2


### Environment

1. OS type and version:  Ubuntu 22.04
2. AlloyDB Proxy version: 1.11.1 +
3. Proxy invocation command (for example, `./alloydb-auth-proxy --port 6000 <INSTANCE_URI>`):


### Additional Details

_No response_