chore: limit nix build to 15 on x86_64-darwin

Author: samrose

docker/nix/build_nix.sh

@@ -5,9 +5,15 @@ nix --version
 if [ -d "/workspace" ]; then
     cd /workspace
 fi
-nix build .#checks.$(nix-instantiate --eval -E builtins.currentSystem | tr -d '"').psql_15 -L --no-link
-nix build .#checks.$(nix-instantiate --eval -E builtins.currentSystem | tr -d '"').psql_16 -L --no-link
-nix build .#psql_15/bin -o psql_15
-nix build .#psql_16/bin -o psql_16
-nix copy --to s3://nix-postgres-artifacts?secret-key=nix-secret-key ./psql_15
-nix copy --to s3://nix-postgres-artifacts?secret-key=nix-secret-key ./psql_16
+if [ $(nix-instantiate --eval -E builtins.currentSystem | tr -d '"') == "x86_64-darwin" ]; then
+    nix build .#checks.$(nix-instantiate --eval -E builtins.currentSystem | tr -d '"').psql_15 -L --no-link
+    nix build .#psql_15/bin -o psql_15
+    nix copy --to s3://nix-postgres-artifacts?secret-key=nix-secret-key ./psql_15
+else
+    nix build .#checks.$(nix-instantiate --eval -E builtins.currentSystem | tr -d '"').psql_15 -L --no-link
+    nix build .#checks.$(nix-instantiate --eval -E builtins.currentSystem | tr -d '"').psql_16 -L --no-link
+    nix build .#psql_15/bin -o psql_15
+    nix build .#psql_16/bin -o psql_16
+    nix copy --to s3://nix-postgres-artifacts?secret-key=nix-secret-key ./psql_15
+    nix copy --to s3://nix-postgres-artifacts?secret-key=nix-secret-key ./psql_16
+fi