[RELEASE] Release opentelemetry-cpp 1.21.0 (open-telemetry#3445)

[RELEASE] Release opentelemetry-cpp 1.20.0 (open-telemetry#3328)

[RELEASE] release opentelemetry-cpp 1.19.0 (open-telemetry#3249)

[RELEASE] Release opentelemetry-cpp 1.18.0 (open-telemetry#3168)

Fixes open-telemetry#3145

[RELEASE] Release opentelemetry-cpp 1.17.0 (open-telemetry#3076)

[RELEASE] Release opentelemetry-cpp version 1.16.1 (open-telemetry#3007)

[RELEASE] Release opentelemetry-cpp version 1.16.0 (open-telemetry#2711)

[RELEASE] Release opentelemetry-cpp version 1.15.0 (open-telemetry#2639)

v1.14.2 release

[RELEASE] Release opentelemetry-cpp version 1.14.1 (open-telemetry#2551)