fix typo: remove redundant space (#3429)

Dockerfile

@@ -6,11 +6,11 @@ RUN apt update -y && \
     apt install -y \
     libssl-dev python-dev sshpass apt-transport-https \
     ca-certificates curl gnupg2 software-properties-common python-pip
-RUN  curl -fsSL https://download.docker.com/linux/ubuntu/gpg | apt-key add - && \
-     add-apt-repository \
-     "deb [arch=amd64] https://download.docker.com/linux/ubuntu \
-     $(lsb_release -cs) \
-     stable" \
-     && apt update -y && apt-get install docker-ce -y
+RUN curl -fsSL https://download.docker.com/linux/ubuntu/gpg | apt-key add - && \
+    add-apt-repository \
+    "deb [arch=amd64] https://download.docker.com/linux/ubuntu \
+    $(lsb_release -cs) \
+    stable" \
+    && apt update -y && apt-get install docker-ce -y
 COPY . .
 RUN /usr/bin/python -m pip install pip -U && /usr/bin/python -m pip install -r tests/requirements.txt && python -m pip install -r requirements.txt