Fixing the upstream link of gsl debian package.

.travis.yml

@@ -41,7 +41,7 @@ install:
     - wget "$sbmlurl" -O libsbml.deb && sudo dpkg -i libsbml.deb 
     - wget http://ftp.debian.org/debian/pool/main/g/gsl/libgsl0ldbl_1.16+dfsg-4_amd64.deb -O gsl_1.16.deb
     - sudo dpkg -i gsl_1.16.deb
-    - wget "http://ftp.debian.org/debian/pool/main/g/gsl/libgsl0-dev_1.16+dfsg-4_amd64.deb" -O gsl_1.16-dev.deb
+    - wget http://ftp.debian.org/debian/pool/main/g/gsl/libgsl0-dev_1.16+dfsg-2_arm64.deb -O gsl_1.16-dev.deb
     - sudo dpkg -i gsl_1.16-dev.deb
     - sudo apt-get install -f
     - sudo ldconfig /usr/lib64