Roll external/abseil_cpp/ 56945519b..8e7767542 (30 commits)

abseil/abseil-cpp@5694551...8e77675

Created with:
  roll-dep external/abseil_cpp

Author: GitHub Actions[bot]

DEPS

@@ -3,7 +3,7 @@ use_relative_paths = True
 vars = {
   'github': 'https://github.com',
 
-  'abseil_revision': '56945519b5d17dcec0982ac6cdf4b6420f03c9c3',
+  'abseil_revision': '8e7767542cfde43f16c142f05dce06cadb7f7f84',
 
   'effcee_revision': '8ce15c424e61a94ee27b5be0ec0ed036b158e6e3',