ci: unset LD_LIBRARY_PATH when using nix

setup-python sets LD_LIBRARY_PATH, which appears to conflict with
nix, and causes nix's python to load a system library instead of
the nix variant.

Author: elopez

scripts/ci_test_dapp.sh

@@ -2,6 +2,11 @@
 
 ### Test dapp integration
 
+# work around having two python versions loading libraries from each other in CI
+OLD_LD_LIBRARY_PATH="$LD_LIBRARY_PATH"
+alias crytic-compile="LD_LIBRARY_PATH=$OLD_LD_LIBRARY_PATH crytic-compile"
+unset LD_LIBRARY_PATH
+
 DIR=$(mktemp -d)
 cd "$DIR" || exit 255