fix: cargo build registry-canister for wasm32 target (#3408)

The following command currently failed to compile the registry canister
if running from the /ic/rs/registery/canister sub-directory:

cargo build --profile canister-release --target wasm32-unknown-unknown
--bin registry-canister

The fix is to make sure the feature `getrandom/custom` is enabled.

Note that the above command would succeed if running from the top-level
directory, but would produce incorrect wasm binary. This is because
cargo would bring in global dependencies that enable both
`getrandom/custom` and `getrandom/js` features, and the latter will lead
to wasm binaries having unwanted imports (See #3309 for more details).

Since this problem does not affect bazel builds, this fix is only
relevant to cargo.

rs/registry/canister/Cargo.toml

@@ -51,6 +51,9 @@ prost = { workspace = true }
 serde = { workspace = true }
 url = { workspace = true }
 
+[target.'cfg(target_arch = "wasm32")'.dependencies]
+getrandom = { version = "0.2", features = [ "custom" ] }
+
 [target.'cfg(not(target_arch = "wasm32"))'.dev-dependencies]
 assert_matches = { workspace = true }
 candid_parser = { workspace = true }