stick to gast 0.3.3, TensorFlow 2.3.1 has a strict version requirement on it

Author: boegel

easybuild/easyconfigs/t/TensorFlow/TensorFlow-2.3.1-foss-2020a-Python-3.8.2.eb

@@ -113,8 +113,8 @@ exts_list = [
     ('astor', '0.8.1', {
         'checksums': ['6a6effda93f4e1ce9f618779b2dd1d9d84f1e32812c23a29b3fff6fd7f63fa5e'],
     }),
-    ('gast', '0.4.0', {
-        'checksums': ['40feb7b8b8434785585ab224d1568b857edb18297e5a3047f1ba012bc83b42c1'],
+    ('gast', '0.3.3', {
+        'checksums': ['b881ef288a49aa81440d2c5eb8aeefd4c2bb8993d5f50edae7413a85bfdb3b57'],
     }),
     ('opt-einsum', '3.3.0', {
         'source_tmpl': 'opt_einsum-%(version)s.tar.gz',