adjust key computation to avoid trailing -

The `-` suffix was being applied unconditionally resulting in a hanging
`-` suffix if no timestamp was used. Adjust the key computation to
remove the trailing `-` if no timestamp is used.

src/restore.ts

@@ -19,9 +19,9 @@ async function restore(ccacheVariant : string) : Promise<void> {
     restoreKeys: core.getInput("restore-keys").split("\n").map(s => s.trim()).filter(x => x !== "")
   };
 
-  const keyPrefix = ccacheVariant + "-";
-  const primaryKey = inputs.primaryKey ? keyPrefix + inputs.primaryKey + "-" : keyPrefix;
-  const restoreKeys = inputs.restoreKeys.map(k => keyPrefix + k + "-")
+  const keyPrefix = ccacheVariant;
+  const primaryKey = inputs.primaryKey ? keyPrefix + "-" + inputs.primaryKey : keyPrefix;
+  const restoreKeys = inputs.restoreKeys.map(k => keyPrefix + "-" + k)
   const paths = [`.${ccacheVariant}`];
 
   core.saveState("primaryKey", primaryKey);

src/save.ts

@@ -62,7 +62,7 @@ async function run() : Promise<void> {
     } else {
       let saveKey = primaryKey;
       if (core.getState("appendTimestamp") == "true") {
-        saveKey += new Date().toISOString();
+        saveKey += "-" + new Date().toISOString();
       } else {
         core.debug("Not appending timestamp because 'append-timestamp' is not set to 'true'.");
       }