Merge branch 'fix-act-walk-caching' into 'master'

BUGFIX: fix act-walk caching

See merge request !1225

(cherry picked from commit e019b5a2)

78a23a7a BUGFIX: fix act-walk caching
3bd9e531 FORMAT: fix formatting issues
76e813ee BUGFIX: typo in _cache attribute
06985f91 BGUFIX: track act for rwalk method
dff3a72c TYPO: add missing blank line
f6017840 TEST: bugfix in dynesty test