Upgrade Docker Anvil Image to CentOS 7

[lilleswing]

CentOS 6.9 has stopped having full support as of May 2017
https://wiki.centos.org/About/Product

The old glibc provided with CentOS 6.9 is causing issues for building tensorflow which requires glibc > 2.14
#802

[mpharrigan]

November 2020

https://wiki.centos.org/FAQ/General#head-fe8a0be91ee3e7dea812e8694491e1dde5b75e6d

[jchodera]

conda-forge already provides tensorflow, and omnia now requires conda-forge as a dependency.

[Lnaden]

But that does not change the fact that the tests are currently failing for that version on deepchem because of libc error seeming to originate from tensorflow, which is really odd exactly because tensorflow is on conda-forge and our docker image is a derivative! But that conversation may best be left to #802 where the problem is occurring.

edited: fixed issue link

[mpharrigan]

do you mean #802

[Lnaden]

d'oh, yes. Incomplete parse of the linked issue on my part

[lilleswing]

@mpharrigan CentOS 6 stopped full support in May 2017. CentOS 6 still has maintenance support through 2020.