Issue #18817: Fix a resource warning in Lib/aifc.py demo.

Lib/aifc.py

@@ -873,6 +873,7 @@ if __name__ == '__main__':
         sys.argv.append('/usr/demos/data/audio/bach.aiff')
     fn = sys.argv[1]
     f = open(fn, 'r')
+    try:
         print("Reading", fn)
         print("nchannels =", f.getnchannels())
         print("nframes   =", f.getnframes())
@@ -884,12 +885,15 @@ if __name__ == '__main__':
             gn = sys.argv[2]
             print("Writing", gn)
             g = open(gn, 'w')
+            try:
                 g.setparams(f.getparams())
                 while 1:
                     data = f.readframes(1024)
                     if not data:
                         break
                     g.writeframes(data)
+            finally:
                 g.close()
-        f.close()
             print("Done.")
+    finally:
+        f.close()

Misc/NEWS

@@ -378,6 +378,8 @@ Documentation
 Tools/Demos
 -----------
 
+- Issue #18817: Fix a resource warning in Lib/aifc.py demo.
+
 - Issue #18439: Make patchcheck work on Windows for ACKS, NEWS.
 
 - Issue #18448: Fix a typo in Tools/demo/eiffel.py.