ENH: Pass FLAIR images to anatomical workflow builder to include in boilerplate (#3146)

Follow-up to nipreps/smriprep#392.

Author: effigies

fmriprep/workflows/base.py

@@ -327,6 +327,7 @@ def init_single_subject_wf(subject_id: str):
         msm_sulc=msm_sulc,
         t1w=subject_data['t1w'],
         t2w=subject_data['t2w'],
+        flair=subject_data['flair'],
         skull_strip_mode=config.workflow.skull_strip_t1w,
         skull_strip_template=Reference.from_string(config.workflow.skull_strip_template)[0],
         spaces=spaces,