Debug build-socrates.sh

- using `set -euo pipefail` for setting recommended failure-modes
- using `set -x` and `echo "$PATH"` to debug my failing build

Sidenote: I find BuildKite's documentation quite helpful!

ci/scripts/build-socrates.sh

@@ -1,3 +1,6 @@
-set -e
+set -euo pipefail
+set -x
+
+echo "$PATH"
 
 /home/wpcarro/.nix-profile/bin/rebuild