remove gpg check as server keep on being unavailable

Dockerfile

@@ -23,12 +23,6 @@ RUN apt-get -q update && \
 ENV TINI_VERSION v0.9.0
 RUN set -x \
     && curl -fSL "https://github.com/krallin/tini/releases/download/$TINI_VERSION/tini" -o /usr/local/bin/tini \
-    && curl -fSL "https://github.com/krallin/tini/releases/download/$TINI_VERSION/tini.asc" -o /usr/local/bin/tini.asc \
-    && export GNUPGHOME="$(mktemp -d)" \
-    && gpg --batch --keyserver hkp://p80.pool.sks-keyservers.net:80 --recv-keys 6380DC428747F6C393FEACA59A84159D7001A4E5 \
-    || gpg --batch --keyserver pgp.mit.edu --recv-keys 6380DC428747F6C393FEACA59A84159D7001A4E5 \
-    && gpg --batch --verify /usr/local/bin/tini.asc /usr/local/bin/tini \
-    && rm -rf "$GNUPGHOME" /usr/local/bin/tini.asc \
     && chmod +x /usr/local/bin/tini
 
 ENTRYPOINT ["/usr/local/bin/tini", "--"]