Travis: why can't we use qpdf appimage?

.travis.yml

@@ -67,7 +67,7 @@ before_install: |
     wget -q 'https://www.dropbox.com/s/vaq0kbwi6e6au80/unpaper_6.1-1.deb?raw=1' -O packages/unpaper_6.1-1.deb
     sudo dpkg -i packages/unpaper_6.1-1.deb
     wget -q 'https://github.com/qpdf/qpdf/releases/download/release-qpdf-8.0.2/qpdf-8.0.2-x86_64.AppImage' -O bin/qpdf
-    chmod +x bin/qpdf  
+    chmod +x bin/qpdf
   elif [[ "$TRAVIS_OS_NAME" == "osx" ]]; then
     brew update && brew bundle --file=.travis/Brewfile
     pip3 install --upgrade pip
@@ -76,6 +76,7 @@ before_install: |
 
 install:
 - export PATH=$PWD/bin:$PATH
+- qpdf --version
 - pip3 install ".$EXTRAS"
 - pip3 install -r test_requirements.txt