Note need to publish with nightly cargo (#506)

Until github.com/rust-lang/cargo/pull/7333 makes it into stable rust,
we'll be forced to publish using nightly, due to our unpublished dev
dependency on `test-utilities`.

Cargo.toml

@@ -40,6 +40,6 @@ pretty_assertions = "0.6"
 
 # Until github.com/rust-lang/cargo/pull/7333 makes it into stable,
 # this version-less dev-dependency will interfere with publishing
-# to crates.io.
+# to crates.io. In the meantime, we can publish with nighlty cargo.
 [dev-dependencies.test-utilities]
 path = "test-utilities"

justfile

@@ -58,7 +58,7 @@ publish-check: lint clippy test
 	git checkout Cargo.lock
 
 publish: publish-check
-	cargo publish
+	cargo +nightly publish
 	git tag -a {{version}} -m 'Release {{version}}'
 	git push github {{version}}