I am developing a wrapper for a bioinformatics tool writen in python3.
The native Galaxy-project runs on python2.7.
How can I the tool that requires python3 in a galaxy-project instance?
Each Galaxy tool uses its own (typically conda-based) environment, which will normally not use the same python as Galaxy itself (note that Galaxy can run under python 3). An example of this is deepTools, which is python 3 only but will happily run under a python 2 Galaxy since conda is being used to create a python 3 environment for it. It's best to distribute your tool via bioconda and then Galaxy will be easily able to install it.