Fix Timer#close signature to not throws IOException

Author: bitterfox

simpleclient/src/main/java/io/prometheus/client/Gauge.java

@@ -1,7 +1,6 @@
 package io.prometheus.client;
 
 import java.io.Closeable;
-import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
@@ -120,10 +119,9 @@ public double setDuration() {
 
      /**
       * Equivalent to calling {@link #setDuration()}.
-      * @throws IOException
       */
      @Override
-     public void close() throws IOException {
+     public void close() {
        setDuration();
      }
    }

simpleclient/src/main/java/io/prometheus/client/Histogram.java

@@ -1,7 +1,6 @@
 package io.prometheus.client;
 
 import java.io.Closeable;
-import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
@@ -175,10 +174,9 @@ public double observeDuration() {
 
     /**
      * Equivalent to calling {@link #observeDuration()}.
-     * @throws IOException
      */
     @Override
-    public void close() throws IOException {
+    public void close() {
       observeDuration();
     }
   }

simpleclient/src/main/java/io/prometheus/client/Summary.java

@@ -3,7 +3,6 @@
 import io.prometheus.client.CKMSQuantiles.Quantile;
 
 import java.io.Closeable;
-import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
@@ -182,10 +181,9 @@ public double observeDuration() {
 
     /**
      * Equivalent to calling {@link #observeDuration()}.
-     * @throws IOException
      */
     @Override
-    public void close() throws IOException {
+    public void close() {
       observeDuration();
     }
   }