slapos: Pin eggs to prevent surprises.

slapos/software.cfg

@@ -18,3 +18,14 @@ list = ${erp5:location}/bt5 ${erp5:location}/product/ERP5/bootstrap ${officejs-a
 <= erp5
 repository = https://lab.nexedi.com/nexedi/officejs-appstore.git
 branch = master
+
+[versions]
+oauth2client = 4.1.0
+pyasn1-modules = 0.0.8
+rsa = 3.4.2
+seaborn = 0.7.1
+statsmodels = 0.8.0
+
+# Required by:
+# statsmodels==0.8.0
+patsy = 0.4.1
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