pgcat fails to start if any of servers is unavailable

[vthriller]

Describe the bug

Subj. pgcat exits with

2023-11-14T04:19:57.260026Z ERROR pgcat::server: Could not connect to server: Connection refused (os error 111)

and error code 78. One faulty server is enough to bring the whole thing down.

To Reproduce

pgcat.toml

[general]

host = "0.0.0.0"
port = 6432
admin_username = "pgcat"
admin_password = "pgcat"

[pools.pool1.users.0]
username = "user"
password = "user"
pool_size = 2
min_pool_size = 1
pool_mode = "transaction"

[pools.pool1.shards.0]
servers = [
  ["127.0.0.1", 55432, "replica"],
  ["127.0.0.1", 55433, "replica"],
]
database = "postgres"

[pools.pool2.users.0]
username = "user"
password = "user"
pool_size = 2
min_pool_size = 1
pool_mode = "transaction"

[pools.pool2.shards.0]
servers = [
  ["127.0.0.1", 55434, "replica"],
  ["127.0.0.1", 55435, "replica"],
]
database = "postgres"

postgres -D pg1 -p 55432 -k /tmp &
postgres -D pg2 -p 55433 -k /tmp &
postgres -D pg3 -p 55434 -k /tmp &
#postgres -D pg4 -p 55435 -k /tmp &
./target/release/pgcat ./pgcat.toml

Expected behavior

pgcat starts normally.

pgcat version

1.1.1

[vthriller]

(BTW, your bug template is unfit for the project. Screenshots? Smartphone browser version?)

[levkk]

validate_config = false

[vthriller]

validate_config = false

Please update sample config file and/or document this in some other way, it's not mentioned anywhere as of 998cc16.

[levkk]

PR welcome.