Allow int8 quantization for export_tfjs (#10948)

* Allow int8 quantization for export_tfjs

--int8 param currently has no effect on export_tfjs. With this change, 
` python export.py --weights ../path/to/best.pt --include tfjs --int8` will add the --quantize_uint8 param to the tensorflowjs_converter script, greatly reducing model size for web usage.

Signed-off-by: David Strahm <david.strahm@lambda-it.ch>

* Update Dockerfile

Signed-off-by: Glenn Jocher <glenn.jocher@ultralytics.com>

---------

Signed-off-by: David Strahm <david.strahm@lambda-it.ch>
Signed-off-by: Glenn Jocher <glenn.jocher@ultralytics.com>
Co-authored-by: Glenn Jocher <glenn.jocher@ultralytics.com>

utils/docker/Dockerfile

@@ -13,13 +13,12 @@ ADD https://ultralytics.com/assets/Arial.ttf https://ultralytics.com/assets/Aria
 ENV DEBIAN_FRONTEND noninteractive
 RUN apt update
 RUN TZ=Etc/UTC apt install -y tzdata
-RUN apt install --no-install-recommends -y gcc git zip curl htop libgl1-mesa-glx libglib2.0-0 libpython3-dev gnupg
+RUN apt install --no-install-recommends -y gcc git zip curl htop libgl1-mesa-glx libglib2.0-0 libpython3-dev gnupg \
+    # Security updates
+    # https://security.snyk.io/vuln/SNYK-UBUNTU1804-OPENSSL-3314796
+    openssl
 # RUN alias python=python3
 
-# Security updates
-# https://security.snyk.io/vuln/SNYK-UBUNTU1804-OPENSSL-3314796
-RUN apt install --no-install-recommends -y openssl
-
 # Create working directory
 RUN rm -rf /usr/src/app && mkdir -p /usr/src/app
 WORKDIR /usr/src/app