ADD: Add PUBLISHER_SPECIFIC flag

Author: threecgreen

CHANGELOG.md

@@ -8,6 +8,7 @@
 #### Enhancements
 - Added `JobState` enum
 - Added export of `SystemCode` and `ErrorCode` from `databento_dbn` to the root `databento` package
+- Added `F_PUBLISHER_SPECIFIC` flag to `RecordFlags` enum
 
 #### Bug fixes
 - Bumped the minimum version requirement for `requests` to 0.27.0

databento/common/enums.py

@@ -207,6 +207,8 @@ class RecordFlags(StringyMixin, IntFlag):  # type: ignore
         The `ts_recv` value is inaccurate (clock issues or reordering).
     F_MAYBE_BAD_BOOK
         Indicates an unrecoverable gap was detected in the channel.
+    F_PUBLISHER_SPECIFIC
+        Indicates a publisher-specific event.
 
     Other bits are reserved and have no current meaning.
 
@@ -218,6 +220,7 @@ class RecordFlags(StringyMixin, IntFlag):  # type: ignore
     F_MBP = 16
     F_BAD_TS_RECV = 8
     F_MAYBE_BAD_BOOK = 4
+    F_PUBLISHER_SPECIFIC = 2
 
 
 @unique