pack.sh: remove references to activator

pack.sh

@@ -5,13 +5,13 @@ set -u
 set -e
 set -o pipefail
 
-"$(which sbt activator | head -n1)" dist
+sbt dist
 
 version=$(
-    "$(which sbt activator | head -n1)" version | tail -n1 | sed 's/^.* //' | grep -oE '[0-9.A-Z-]+' | head -n2 | tail -n1
+    sbt version | tail -n1 | sed 's/^.* //' | grep -oE '[0-9.A-Z-]+' | head -n2 | tail -n1
 )
 scalaVersion=$(
-    "$(which sbt activator | head -n1)" server/scalaVersion | tail -n1 | sed 's/^.* //' | grep -oE '[0-9.A-Z-]+' | head -n2 | tail -n1 | sed 's/^\([^.]*.[^.]*\).*/\1/'
+    sbt server/scalaVersion | tail -n1 | sed 's/^.* //' | grep -oE '[0-9.A-Z-]+' | head -n2 | tail -n1 | sed 's/^\([^.]*.[^.]*\).*/\1/'
 )
 
 if [ -e target/assets ]; then