fix(php): use PR branch to build imagick

remove this after Imagick/imagick#641 has been
merged and released.

shared/php/rootfs/tmp/install-php.sh

@@ -54,7 +54,21 @@ apk add --no-cache php$PHP_VERSION \
     gcc \
     musl-dev
 
-pecl$PHP_VERSION install imagick
+# install imagick from PR
+#     https://github.com/Imagick/imagick/pull/641
+# replace the routine with this command after PR has been merged:
+#     pecl$PHP_VERSION install imagick 
+cd /tmp
+wget -O imagick.tar.gz https://github.com/FedericoHeichou/imagick/archive/7088edc353f53c4bc644573a79cdcd67a726ae16.tar.gz
+tar xvfz imagick.tar.gz
+cd imagick-7088edc353f53c4bc644573a79cdcd67a726ae16
+phpize$PHP_VERSION
+./configure --with-php-config=/usr/bin/php-config$PHP_VERSION --with-imagick
+make
+make install
+cd /
+rm -rf /tmp/imagick*
+
 echo "extension=imagick.so" > /etc/php$PHP_VERSION/conf.d/00_imagick.ini
 
 # remove dev dependencies