Only extract downloaded current tar archive

The current postinst has the bug that all tar archives store in /opt
that begin with ideaIC- are extracted. While this issue will not appear
to most users it may still be a problem to aborted installations which
are only continued after an update.

Fixes issue #5

intellij-idea-community_2021.2.2/debian/postinst

@@ -5,13 +5,13 @@ set -e
 cd /opt/
 
 ## Extract the package
-sudo tar xf /opt/ideaIC-*
+sudo tar xf /opt/ideaIC-2021.2.2.tar.gz
 
 ## Rename the directory
 sudo mv /opt/idea-IC-* /opt/intellij-idea-community
 
 ## Remove  the tar.gz package
-sudo rm /opt/ideaIC-*
+sudo rm /opt/ideaIC-2021.2.2.tar.gz
 
 ## Install the .desktop file, if necessary
 if [ -x "/usr/bin/desktop-file-install" ]; then

update-new-version.sh

@@ -26,6 +26,7 @@ main() {
 	"Upstream version $new"
 
     sed -i "s/$old/$new/g" ./debian/preinst
+    sed -i "s/$old/$new/g" ./debian/postinst
 
     debuild -us -uc