Add architecture detection for WKHTMLtoX installation

If Apple silicon version of Docker Desktop is installed then some containers will be
for arm64 architecture instead of amd64.
So when installing WKHTMLtoX a proper package has to be installed.

workspace/Dockerfile

@@ -1442,7 +1442,8 @@ USER root
 ARG INSTALL_WKHTMLTOPDF=false
 
 RUN if [ ${INSTALL_WKHTMLTOPDF} = true ]; then \
-   apt-get install -y \
+   ARCH=$(arch | sed s/aarch64/arm64/ | sed s/x86_64/amd64/) \
+   && apt-get install -y \
    libxrender1 \
    libfontconfig1 \
    libx11-dev \
@@ -1453,8 +1454,8 @@ RUN if [ ${INSTALL_WKHTMLTOPDF} = true ]; then \
    xfonts-base \
    xfonts-75dpi \
    wget \
-   && wget https://github.com/wkhtmltopdf/packaging/releases/download/0.12.6-1/wkhtmltox_0.12.6-1.bionic_amd64.deb \
-   && dpkg -i wkhtmltox_0.12.6-1.bionic_amd64.deb \
+   && wget "https://github.com/wkhtmltopdf/packaging/releases/download/0.12.6-1/wkhtmltox_0.12.6-1.bionic_${ARCH}.deb" \
+   && dpkg -i "wkhtmltox_0.12.6-1.bionic_${ARCH}.deb" \
    && apt -f install \
 ;fi