cargo xtask install fails with database connection errors

[mmoncure]

Sorry, this likely an obvious problem, but I'm stuck!

Getting (error: error communicating with database: Connection refused (os error 61))

To Reproduce

error: error communicating with database: Connection refused (os error 61)
  --> crates/pg_schema_cache/src/versions.rs:17:9
   |
17 | /         sqlx::query_as!(
18 | |             Version,
19 | |             r#"select
20 | |   version(),
...  |
28 | |   current_setting('max_connections') :: int8 AS max_connections;"#
29 | |         )
   | |_________^
   |
   = note: this error originates in the macro `$crate::sqlx_macros::expand_query` which comes from the expansion of the macro `sqlx::query_as` (in Nightly builds, run with -Z macro-backtrace for more info)

Expected behavior

I can connect with psql with no arguments due to how environment is set -- what is the build using to connect, and to what?

System information

macOS