Fix indentation in Dockerfile

Dockerfile

@@ -8,41 +8,41 @@ COPY . /app
 RUN apt-get update && \
     apt-get install -y \
         build-essential \
-	autoconf \
-	libtool \
-	git \
-	bison \
-	flex \
-	ruby \
-	wget \
-	ruby-dev && \
+        autoconf \
+        libtool \
+        git \
+        bison \
+        flex \
+        ruby \
+        wget \
+        ruby-dev && \
     wget http://www.geocities.jp/kosako3/oniguruma/archive/onig-5.9.6.tar.gz && \
     sha512sum onig-5.9.6.tar.gz | grep 4a181ea6f0e1a018bbaf6c87e666dfffd1ef4b8f5dcead07fa0b6564a76174e7e01854173924668433ae74c455dbced6a0e1b43e9066f0499b4a57e855e1a2b2 && \
     tar zxvf onig-5.9.6.tar.gz && \
     (cd onig-5.9.6 && \
         ./configure --prefix=/usr/local && \
         make && \
-	make install ) && \
+        make install ) && \
     gem install bundler && \
     (cd /app/docs && bundle install) && \
     (cd /app && \
         autoreconf -i && \
         ./configure --disable-valgrind --enable-all-static --prefix=/usr/local && \
-	make -j8 && \
-	make check && \
-	make install && \
-	make distclean ) && \
+        make -j8 && \
+        make check && \
+        make install && \
+        make distclean ) && \
     (cd onig-5.9.6 && \
         make uninstall ) && \
     apt-get purge -y \
         build-essential \
-	autoconf \
-	libtool \
-	bison \
-	git \
-	flex \
-	ruby \
-	ruby-dev && \
+        autoconf \
+        libtool \
+        bison \
+        git \
+        flex \
+        ruby \
+        ruby-dev && \
     apt-get autoremove -y && \
     rm -rf onig-5.9.6 && \
     rm -rf /var/lib/apt/lists/* /var/lib/gems