stop relying on python being in the PATH

Author: RalfJung

miri

@@ -40,7 +40,7 @@ TARGET=$(rustc --version --verbose | grep "^host:" | cut -d ' ' -f 2)
 SYSROOT=$(rustc --print sysroot)
 LIBDIR=$SYSROOT/lib/rustlib/$TARGET/lib
 # macOS does not have a useful readlink/realpath so we have to use Python instead...
-MIRIDIR=$(dirname "$(python -c 'import os, sys; print(os.path.realpath(sys.argv[1]))' "$0")")
+MIRIDIR=$(dirname "$(python3 -c 'import os, sys; print(os.path.realpath(sys.argv[1]))' "$0")")
 if ! test -d "$LIBDIR"; then
     echo "Something went wrong determining the library dir."
     echo "I got $LIBDIR but that does not exist."