Disable pager for ci script

[richvdh]

... otherwise it hangs

[codecov-io]

Codecov Report

Merging #4291 into develop will decrease coverage by 0.01%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           develop    #4291      +/-   ##
===========================================
- Coverage    73.49%   73.48%   -0.02%     
===========================================
  Files          302      302              
  Lines        29892    29892              
  Branches      4887     4887              
===========================================
- Hits         21968    21965       -3     
- Misses        6488     6491       +3     
  Partials      1436     1436

Impacted Files	Coverage Δ
synapse/util/file_consumer.py	80.7% <0%> (-1.76%)	⬇️
synapse/app/homeserver.py	56.53% <0%> (-0.33%)	⬇️
synapse/handlers/user_directory.py	70.73% <0%> (-0.31%)	⬇️
synapse/handlers/search.py	80.24% <0%> (ø)	⬆️
synapse/handlers/federation.py	61.72% <0%> (ø)	⬆️

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