Update abseil submodule to HEAD
Update abseil submodule to HEAD

Abseil suggests to use the latest code:
https://abseil.io/about/philosophy#we-recommend-that-you-choose-to-live-at-head

Signed-off-by: Stefan Weil <8d4c780fcfdc41841e5070f4c43da8958ba6aec0@weilnetz.de>

UB-Mannheim/tesseract,tesseract-ocr/tesseract,UB-Mannheim/tesseract,tesseract-ocr/tesseract,amitdo/tesseract,amitdo/tesseract,amitdo/tesseract,stweil/tesseract,tesseract-ocr/tesseract,stweil/tesseract,amitdo/tesseract,amitdo/tesseract,stweil/tesseract,stweil/tesseract,tesseract-ocr/tesseract,stweil/tesseract,UB-Mannheim/tesseract,tesseract-ocr/tesseract,UB-Mannheim/tesseract,UB-Mannheim/tesseract