Force GSL version to 2.7 for pyodide build
Force GSL version to 2.7 for pyodide build

Signed-off-by: Jo Bovy <5f4740866519f9416189f7917fd84b4195ada6bc@astro.utoronto.ca>

jobovy/galpy,jobovy/galpy,jobovy/galpy,jobovy/galpy