Update build instructions for future (emscripten-forge#2623)

* Update build instructions for future

* Update import test

Author: IsabelParedes

recipes/recipes_emscripten/future/build.sh

@@ -10,13 +10,15 @@ source:
   sha256: bd2968309307861edae1458a4f8a4f3598c03be43b97521076aebf5d94c07b05
 
 build:
-  number: 1
+  number: 2
+  script: ${{ PYTHON }} -m pip install . ${{ PIP_ARGS }}
 
 requirements:
   build:
   - python
   - pip
   - ${{ compiler("cxx") }}
+  - cross-python_${{ target_platform }}
   host:
   - python
 
@@ -31,9 +33,9 @@ tests:
     run:
     - pytester-run
 
-
 about:
-  homepage: http://python-future.org
+  homepage: https://python-future.org
+  repository: https://github.com/PythonCharmers/python-future
   license: MIT
   license_family: MIT
   license_file: LICENSE.txt

recipes/recipes_emscripten/future/recipe.yaml

@@ -1,3 +1,8 @@
 
 def test_import_future():
-    import __future__
+    from future.builtins import iterators
+    from future.utils import (old_div, istext, isbytes, native, PY2, PY3,
+                            native_str, raise_, as_native_str, ensure_new_type,
+                            bytes_to_native_str, raise_from)
+    from future.tests.base import expectedFailurePY3
+    from future.tests.base import unittest, skip26