Bump protobuf from 3.5.2 to 3.6.1

[dependabot-preview]

Bumps protobuf from 3.5.2 to 3.6.1.

Release notes

Sourced from protobuf's releases.

Protocol Buffers v3.6.1

C++

• Introduced workaround for Windows issue with std::atomic and std::once_flag initialization (#4777, #4773)

PHP

• Added compatibility with PHP 7.3 (#4898)

Ruby

• Fixed Ruby crash involving Any encoding (#4718)

Protocol Buffers v3.6.0

General

• We are moving protobuf repository to its own github organization (see https://github-redirect.dependabot.com/google/protobuf/issues/4796). Please let us know what you think about the move by taking this survey: https://docs.google.com/forms/d/e/1FAIpQLSeH1ckwm6ZrSfmtrOjRwmF3yCSWQbbO5pTPqPb6_rUppgvBqA/viewform

C++

• Starting from this release, we now require C++11. For those we cannot yet upgrade to C++11, we will try to keep the 3.5.x branch updated with critical bug fixes only. If you have any concerns about this, please comment on issue #2780.
• Moved to C++11 types like std::atomic and std::unique_ptr and away from our old custom-built equivalents.
• Added support for repeated message fields in lite protos using implicit weak fields. This is an experimental feature that allows the linker to strip out more unused messages than previously was possible.
• Fixed SourceCodeInfo for interpreted options and extension range options.
• Fixed always_print_enums_as_ints option for JSON serialization.
• Added support for ignoring unknown enum values when parsing JSON.
• Create std::string in Arena memory.
• Fixed ValidateDateTime to correctly check the day.
• Fixed bug in ZeroCopyStreamByteSink.
• Various other cleanups and fixes.

Java

• Dropped support for Java 6.
• Added a UTF-8 decoder that uses Unsafe to directly decode a byte buffer.
• Added deprecation annotations to generated code for deprecated oneof fields.
• Fixed map field serialization in DynamicMessage.
• Cleanup and documentation for Java Lite runtime.
• Various other fixes and cleanups
• Fixed unboxed arraylists to handle an edge case
• Improved performance for copying between unboxed arraylists
• Fixed lite protobuf to avoid Java compiler warnings
• Improved test coverage for lite runtime
• Performance improvements for lite runtime

Python

• Fixed bytes/string map key incompatibility between C++ and pure-Python implementations (issue #4029)
• Added __init__.py files to compiler and util subpackages
• Use /MT for all Windows versions
• Fixed an issue affecting the Python-C++ implementation when used with Cython (issue #2896)
• Various text format fixes
• Various fixes to resolve behavior differences between the pure-Python and Python-C++ implementations

PHP

• Added php_metadata_namespace to control the file path of generated metadata file.
• Changed generated classes of nested message/enum. E.g., Foo.Bar, which previously generates Foo_Bar, now generates Foo/Bar

... (truncated)

Commits

• 48cb18e Updated change log for 3.6.1 release
• 9e1286b Updated version numbers to 3.6.1
• e508fc0 Check the message to be encoded is the wrong type. (#4885) (#4949)
• fc90fd6 Make assertEquals pass for message (#4947)
• d85ffdc Merge pull request #4924 from xfxyjwf/3.6.x
• 8356d27 Add continuous test for ruby 2.3, 2.4 and 2.5 (#4829)
• 7fdebf2 Fix cpp_distcheck
• 6c82411 Fix php conformance test.
• 11e2eca protoc-artifacts: Update centos base from 6.6 to 6.9
• 6fc2bac Updated Docker setup to use GCC 4.8
• Additional commits viewable in compare view

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[dependabot-preview]

Superseded by #53.