Is the Sabbath part of the “special days and months and seasons and years” Paul is referring to in Galatians 4:10?

Galatians 4:8-11 (NIV) says: 8 Formerly, when you did not know God, you were slaves to those who by nature are not gods. 9 But now that you know God—or rather are known by God—how is it that you are turning back to those weak and miserabl…