I have a point table containing values ranging from 0 to 100 and I would like to draw a contour line for the value 70. (See image below)

I know how to create contour lines in QGIS for raster data but now I would like to do it with vector data (my point table) using PostGIS so that it can be integrated in a python script.

Any idea on how to start?

EDIT:
This question is different from [Generating contour lines and filled contours from points](https://gis.stackexchange.com/questions/42020/generating-contour-lines-and-filled-contours-from-points) as it doesn't involve raster data (neither in the input nor in the output)

[![enter image description here](https://i.stack.imgur.com/qNIbw.png)](https://i.stack.imgur.com/qNIbw.png)