Add support for OpenTelemetry tracing via OTLP

This allows using the GRPC endpoint of an OTLP exporter to export
span-based telemetry data directly from conmon-rs.

Signed-off-by: Sascha Grunert <sgrunert@redhat.com>

.github/install-deps

@@ -2,4 +2,4 @@
 set -euo pipefail
 
 sudo apt-get update
-sudo apt-get install capnproto runc
+sudo apt-get install capnproto runc protobuf-compiler

.github/workflows/cross.yml

@@ -7,7 +7,6 @@ on:
 env:
   CROSS_VERSION: v0.2.4
   CARGO_TERM_COLOR: always
-  ACTION_MSRV_TOOLCHAIN: 1.58.1
 jobs:
   build:
     strategy:
@@ -31,13 +30,6 @@ jobs:
             ~/.cargo/git
             target
           key: ${{ runner.os }}-cross-${{matrix.arch}}-${{ hashFiles('**/Cargo.lock') }}
-      - name: Select Toolchain
-        uses: actions-rs/toolchain@v1
-        with:
-          toolchain: ${{ env['ACTION_MSRV_TOOLCHAIN']  }}
-          default: true
-          override: true
-          components: rustfmt
       - name: Install cross-rs
         run: |
           curl -sSfL --retry 5 --retry-delay 3 \