Bump Google.Protobuf from 3.12.4 to 3.15.3 in /dotnet-etcd

[dependabot]

Bumps Google.Protobuf from 3.12.4 to 3.15.3.

Release notes

Sourced from Google.Protobuf's releases.

Protocol Buffers v3.15.3

Ruby

• Ruby <2.7 now uses WeakMap too, which prevents memory leaks. (#8341)

Protocol Buffers v3.15.2

Ruby

• Fix for FieldDescriptor.get(msg) (#8330)

C++

• Fix PROTOBUF_CONSTINIT macro redefinition (#8323)

Protocol Buffers v3.15.1

Ruby

• Bugfix for Message.[] for repeated or map fields (#8313)
• Fix for truncating behavior when converting Float to Duration (#8320)

C++

• Small fixes for MinGW and for C++20 with GCC (#8318)

Protocol Buffers v3.15.0

Protocol Compiler

• Optional fields for proto3 are enabled by default, and no longer require the --experimental_allow_proto3_optional flag.

C++

• MessageDifferencer: fixed bug when using custom ignore with multiple unknown fields
• Use init_seg in MSVC to push initialization to an earlier phase.
• Runtime no longer triggers -Wsign-compare warnings.
• Fixed -Wtautological-constant-out-of-range-compare warning.
• DynamicCastToGenerated works for nullptr input for even if RTTI is disabled
• Arena is refactored and optimized.
• Clarified/specified that the exact value of Arena::SpaceAllocated() is an implementation detail users must not rely on. It should not be used in unit tests.
• Change the signature of Any::PackFrom() to return false on error.
• Add fast reflection getter API for strings.
• Constant initialize the global message instances
• Avoid potential for missed wakeup in UnknownFieldSet
• Now Proto3 Oneof fields have "has" methods for checking their presence in C++.
• Bugfix for NVCC
• Return early in _InternalSerialize for empty maps.
• Adding functionality for outputting map key values in proto path logging output (does not affect comparison logic) and stop printing 'value' in the path. The modified print functionality is in the MessageDifferencer::StreamReporter.
• Fixed protocolbuffers/protobuf#8129
• Ensure that null char symbol, package and file names do not result in a crash.

... (truncated)

Commits

• 983d115 Update protobuf version
• eb542e6 Updated CHANGES.txt for 3.15.3 release
• 80ec787 Merge pull request #8341 from haberman/ruby-2.5-gc
• 9879f42 Ruby <2.7now uses WeakMap too, which prevents memory leaks.
• d7e943b Update protobuf version
• 1af4657 Updated CHANGES.txt
• 09f94e7 Fix PROTOBUF_CONSTINIT macro redifinition
• 2ff31d3 Merge pull request #8330 from haberman/rubyfix
• 4e3ea74 [Ruby] Fix for FieldDescriptor.get(msg).
• 052dc79 Update protobuf version
• Additional commits viewable in compare view

Dependabot will resolve any conflicts with this PR as long as you don't alter it yourself. You can also trigger a rebase manually by commenting @dependabot rebase.

---

Dependabot commands and options

You can trigger Dependabot actions by commenting on this PR:

• @dependabot rebase will rebase this PR
• @dependabot recreate will recreate this PR, overwriting any edits that have been made to it
• @dependabot merge will merge this PR after your CI passes on it
• @dependabot squash and merge will squash and merge this PR after your CI passes on it
• @dependabot cancel merge will cancel a previously requested merge and block automerging
• @dependabot reopen will reopen this PR if it is closed
• @dependabot close will close this PR and stop Dependabot recreating it. You can achieve the same result by closing it manually
• @dependabot ignore this major version will close this PR and stop Dependabot creating any more for this major version (unless you reopen the PR or upgrade to it yourself)
• @dependabot ignore this minor version will close this PR and stop Dependabot creating any more for this minor version (unless you reopen the PR or upgrade to it yourself)
• @dependabot ignore this dependency will close this PR and stop Dependabot creating any more for this dependency (unless you reopen the PR or upgrade to it yourself)

[dependabot]

Dependabot tried to add @shubhamranjan as a reviewer to this PR, but received the following error from GitHub:

POST https://api.github.com/repos/sergey-kucheruk/dotnet-etcd/pulls/17/requested_reviewers: 422 - Reviews may only be requested from collaborators. One or more of the users or teams you specified is not a collaborator of the sergey-kucheruk/dotnet-etcd repository. // See: https://docs.github.com/rest/reference/pulls#request-reviewers-for-a-pull-request

[dependabot]

Superseded by #20.