bump golang/protobuf v1.3.2

full diff: golang/protobuf@v1.2.0...v1.3.2

protobuf v1.3.2:

- golang/protobuf#785: grpc code generation: add an UnimplementedServer type implementing each server interface, returning an unimplemented error for each method
- golang/protobuf#851: convert prints to os.Stderr to use log.Printf
- golang/protobuf#883: jsonpb: fix marshaling of Duration with negative nanoseconds

protobuf v1.3.1:

- The set of dependencies specified in go.mod has now been reduced to only the standard library.

protobuf v1.3.0:

- golang/protobuf#699: add a go.mod module file
- golang/protobuf#701: stop generating package "// import" comment
- golang/protobuf#741: deprecate {Unm,M}arshalMessageSet{JSON}
- golang/protobuf#760: different internal implementation of oneofs
    - `.pb.go` files generated by protoc-gen-go@v1.3.0 will require the proto@v1.3.0 package to work
- various minor changes to code generation

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

vendor.conf

@@ -10,7 +10,7 @@
 # string matching there is correct.
 google.golang.org/grpc 25c4f928eaa6d96443009bd842389fb4fa48664e # v1.20.1
 github.com/gogo/protobuf ba06b47c162d49f2af050fb4c75bcbc86a159d5c # v1.2.1
-github.com/golang/protobuf aa810b61a9c79d51363740d207bb46cf8e620ed5 # v1.2.0
+github.com/golang/protobuf 6c65a5562fc06764971b7c5d05c76c75e84bdbf7 # v1.3.2
 github.com/matttproud/golang_protobuf_extensions c12348ce28de40eed0136aa2b644d0ee0650e56c # v1.0.1
 google.golang.org/genproto 694d95ba50e67b2e363f3483057db5d4910c18f9