Port mtcnn to Tensorflow 2

Using the TF1 model.pb

I couldn't manage to optimize the tf2 python version yet so here is the version that loads the frozen graph.

added 2 commits

• 986ffe9d - [annotator] Removing tf device definition
• 35c48369 - [annotator] Reorganize the mtcnn file structure.

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added 1 commit

• a66d18cb - [annotator] Default transform behavior

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added 2 commits

• f305bae5 - [conda] Add tf2 as optional and test requirements.
• 3f210578 - [annotator] MTCNN Annotator class in bob.bio.face.

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added 1 commit

• 1dcfa89c - [doc] fix mtcnn annotations plot script

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mentioned in merge request docs!20 (merged)

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• 8fd2c343 - Keep the old API of MTCNN

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• 137921e1 - [MANIFEST.in] Also include .png files from data folder

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• 6d9b728f - [MANIFEST.in] Also include .pb files from data folder

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added 1 commit

• 18833067 - [conda] make tensorflow Linux only

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resolved all threads

enabled an automatic merge when the pipeline for 18833067 succeeds

aborted the automatic merge because source branch was updated

added 1 commit

• c8c88696 - [doc] only run mtcnn example when tf is available

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enabled an automatic merge when the pipeline for c8c88696 succeeds

aborted the automatic merge because source branch was updated

added 1 commit

• 4cd4481e - [doc] only run mtcnn example when tf is available

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enabled an automatic merge when the pipeline for 4cd4481e succeeds

merged

mentioned in commit 07be3e8d

Thank you @ydayer