Reorder digest algorithms proto message fields.

This is safe because the code is not deployed anywhere yet.

proto/rrg/action/get_file_metadata.proto

@@ -37,14 +37,14 @@ message Args {
   // Supported only if the `action-get_file_metadata-sha1` feature is enabled.
   //
   // [1]: https://en.wikipedia.org/wiki/SHA-1
-  bool sha1 = 5;
+  bool sha1 = 4;
 
   // Whether to collect [SHA-256 digest][2] of the file contents.
   //
   // Supported only if the `action-get_file_metadata-sha256` feature is enabled.
   //
   // [1]: https://en.wikipedia.org/wiki/SHA-2
-  bool sha256 = 4;
+  bool sha256 = 5;
 }
 
 message Result {
@@ -81,13 +81,13 @@ message Result {
   // and `sha1` argument was provided.
   //
   // [1]: https://en.wikipedia.org/wiki/SHA-1
-  bytes sha1 = 7;
+  bytes sha1 = 6;
 
   // [SHA-256 digest][1] of the file contents.
   //
   // Collected only if the `action-get_file_metadata-sha256` feature is enabled
   // and `sha256` argument was provided.
   //
   // [1]: https://en.wikipedia.org/wiki/SHA-2
-  bytes sha256 = 6;
+  bytes sha256 = 7;
 }