Add riscv64 arch (open-telemetry#41496)

<!--Ex. Fixing a bug - Describe the bug and how this fixes the issue.
Ex. Adding a feature - Explain what this achieves.-->
#### Description

New Tier 3 platform: `riscv64` architecture is now included, allowing
the collector to be built and distributed for this platform.

<!-- Issue number (e.g. #1234) or full URL to issue, if applicable. -->
#### Link to tracking issue
Fixes open-telemetry#41507
X-Ref:
open-telemetry/opentelemetry-collector-releases#969

<!--Describe what testing was performed and which tests were added.-->
#### Testing

I’ve performed basic compilation as well as starting collector inside a
linux/riscv64 container (`docker.io/riscv64/debian`).

---------

Signed-off-by: Mateusz Urbanek <mateusz.urbanek.98@gmail.com>

Author: shanduur

.chloggen/rv64.yaml

@@ -0,0 +1,25 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: enhancement
+
+# The name of the component, or a single word describing the area of concern, (e.g. otlpreceiver)
+component: architecture
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: New Tier 3 platform riscv64 allowing the collector to be built and distributed for this platform.
+
+# One or more tracking issues or pull requests related to the change
+issues: [ 41507 ]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:
+
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: []

.github/workflows/build-and-test.yml

@@ -337,7 +337,7 @@ jobs:
           else
             echo "Tests passed or were skipped. Continuing."
           fi
-          
+
   unittest:
     if: ${{ github.actor != 'dependabot[bot]' && always() }}
     runs-on: ubuntu-24.04
@@ -544,6 +544,7 @@ jobs:
           - arm
           - arm64
           - ppc64le
+          - riscv64
           - s390x
         include:
           - os: linux
@@ -556,6 +557,8 @@ jobs:
             arch: arm
           - os: darwin
             arch: ppc64le
+          - os: darwin
+            arch: riscv64
           - os: darwin
             arch: s390x
           - os: windows
@@ -564,6 +567,8 @@ jobs:
             arch: arm64
           - os: windows
             arch: ppc64le
+          - os: windows
+            arch: riscv64
           - os: windows
             arch: s390x
     steps:

.github/workflows/telemetrygen.yml

@@ -103,7 +103,7 @@ jobs:
           context: cmd/telemetrygen
           push: true
           tags: ghcr.io/open-telemetry/opentelemetry-collector-contrib/telemetrygen:latest
-          platforms: linux/amd64,linux/arm64,linux/s390x,linux/ppc64le
+          platforms: linux/amd64,linux/arm64,linux/s390x,linux/ppc64le,linux/riscv64
 
   publish-stable:
     runs-on: ubuntu-24.04