dev-tools/pull-request.sh: default to php7 branch
dev-tools/pull-request.sh: default to php7 branch

php/pecl-file_formats-yaml,bd808/pecl-file_formats-yaml,bd808/pecl-file_formats-yaml,php/pecl-file_formats-yaml,bd808/pecl-file_formats-yaml,bd808/pecl-file_formats-yaml,php/pecl-file_formats-yaml,php/pecl-file_formats-yaml