pins 1.2.0

Breaking changes

• pin_write() no longer writes identical pin contents by default, and gains a
  force_identical_write argument for writing even when the pin contents are
  identical to the last version (#735).

Other improvements

• The print method for boards no longer calls pin_list() internally (#718).

• board_s3() now uses pagination for listing and versioning (#719, @mzorko).

• Added type = "parquet" to read and write Parquet files (#729).

• Updated error messages and type checking (#731) along with testing strategy (#724).

• Added new check for whether a new version is the same as the previous version,
  as can happen when writing pin versions very quickly (#727).

• Added new headers argument for board_url(), mostly for authentication, as
  well as new board for Connect vanity URLs board_connect_url() (#732).

• Fixed bug in cache_prune() to correctly find caches for board_url() (#734).