Update Dockerfile

phar.readonly by default is set to "1". This causes the following error:

ERROR: Cannot create phar: phar.readonly is set to 1

When generating a phar. This commit disables readonly, allowing the phar to generate

Dockerfile

@@ -4,6 +4,6 @@ COPY . /phpggc
 
 WORKDIR /phpggc
 
-RUN chmod +x phpggc
+RUN chmod +x phpggc && echo "phar.readonly=0" > $PHP_INI_DIR/php.ini
 
-ENTRYPOINT ["/phpggc/phpggc"]
+ENTRYPOINT ["/phpggc/phpggc"]