Fixes AutoTST installation on BSD sed

Ensures compatibility of the AutoTST installation script with both GNU and BSD versions of `sed`. It achieves this by conditionally including an empty string in the `sed -i` command for BSD systems, which require it.

Author: calvinp0

devtools/install_autotst.sh

@@ -173,8 +173,13 @@ autotst_off () {
 # Enable AutoTST by default in new shells and keep RMG-Py out of the way.
 autotst_on
 EOF
-        # replace placeholder with actual path
-        sed -i "s#__AUTOTST_PATH__#$(pwd | sed 's#/#\\\\/#g')#" ~/.bashrc
+        # replace placeholder with actual path (portable across GNU/BSD sed)
+        AUTOTST_ESCAPED_PATH="$(pwd | sed 's#/#\\\\/#g')"
+        if sed --version >/dev/null 2>&1; then
+            sed -i "s#__AUTOTST_PATH__#${AUTOTST_ESCAPED_PATH}#" ~/.bashrc
+        else
+            sed -i '' "s#__AUTOTST_PATH__#${AUTOTST_ESCAPED_PATH}#" ~/.bashrc
+        fi
         echo "✔️ Added AutoTST path-mode hook to ~/.bashrc"
     else
         echo "ℹ️ AutoTST path-mode hook already exists in ~/.bashrc"