fix: remove leading and trailing - caracter

README.md

@@ -6,7 +6,8 @@ This action slug and expose some github variables.
 
 - put the variable content in lower case,
 - replace any caracter by `-` except `0-9` and `a-z`,
-- limit the string size to 63 caracters
+- remove leading and trailing `-` caracter,
+- limit the string size to 63 caracters.
 
 ## Environement Variables
 

entrypoint.sh

@@ -3,6 +3,7 @@
 slug_ref() {
     echo "$1" \
          | tr "[:upper:]" "[:lower:]" \
+         | sed -r 's#refs/.*/##;s/[~\^]+//g;s/[^a-zA-Z0-9]+/-/g;s/^-+\|-+$//g;s/^-*//;s/-*$//' \
          | cut -c1-63
 }