Log Message:
protobuf py-protobuf: updated to 3.20.0

Protocol Buffers v3.20.0

C++

Add option to use external GTest in CMake
cmake: Set correct sonames for libprotobuf-lite.so and libprotoc.so
Java

Revert "Standardize on Array copyOf"
Resolve more java field accessor name conflicts

Python

Pin multibuild scripts to get manylinux1 wheels back
Dropped support for Python < 3.7

PHP

fix: [PHP] add missing reserved classnames

Ruby

Dropped Ruby 2.3 and 2.4 support for CI and releases.
[Ruby] Message.decode/encode: Add max_recursion_depth option
Ruby: rename max_recursion_depth to recursion_limit
Fix conversion of singleton classes in Ruby
Suppress warning for intentional circular require
[Ruby] allow encode json options to be an object that responds to to_hash

Other

[C#] Fix trim warnings
Add protoc-gen-go-svc to options.md
Fixes NullReferenceException when accessing FieldDescriptor.IsPacked
Add ToProto() method to all C# descriptor classes
Add cmake option protobuf_INSTALL to not install files
[CMake] Allow custom plugin options e.g. to generate mocks
Add an option to preserve proto names in JsonFormatter
Add test scope to kotlin-test for protobuf-kotlin-lite
Add prefix_to_proto_package_mappings_path ObjC option.
[ObjC] Rename proto_package_to_prefix_mappings_path to \ 
package_to_prefix_mappings_path.
cmake: Use linker version scripts
Add a generation option to control use of forward declarations in headers.
[C#] fix parse failure for extensions with large field numbers