Merge branch 'rf/imglob-perf' into 'master'

MNT: Improve performance of im* scripts

See merge request fsl/fslpy!310
6 jobs for master in 11 minutes and 31 seconds (queued for 4 seconds)
Status Name Job ID Coverage
  Test
passed test:3.7 #49685
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00:11:13

94.0%
canceled test:3.8 #49707
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00:00:01

passed test:3.9 #49687
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00:11:29

94.0%
passed test:build-pypi-dist #49688
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00:01:09

canceled test:3.8 #49686
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00:18:10

 
  Style
canceled style #49689
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