Fix version/upgrade check command for .deb packaging

A typo in the Debian preinst/postinst files used for package compilation was causing dpkg to exit with an error code while attempting to install the .deb package.

src/deb/hestia/postinst

@@ -18,7 +18,7 @@ fi
 
 # Set new hestia version in conf file
 if [ "$VERSION" != "$version" ]; then
-    sed -I "s/VERSION='$VERSION'/VERSION='$version'/" /usr/local/hestia/conf/hestia.conf
+    sed -i "s/VERSION='$VERSION'/VERSION='$version'/g" /usr/local/hestia/conf/hestia.conf
 fi
 
 exit 0

src/deb/hestia/preinst

@@ -13,5 +13,5 @@ version=$(dpkg -l | awk '$2=="hestia" { print $3 }')
 
 # Set hestia version if different.
 if [ "$VERSION" != "$version" ]; then
-    sed -I "s/VERSION='$VERSION'/VERSION='$version'/" /usr/local/hestia/conf/hestia.conf
+    sed -i "s/VERSION='$VERSION'/VERSION='$version'/g" /usr/local/hestia/conf/hestia.conf
 fi