add an sdk workflow input param (#70)

diff --git a/.github/workflows/publish.yaml b/.github/workflows/publish.yaml
index 30cad38..8d417c4 100644
--- a/.github/workflows/publish.yaml
+++ b/.github/workflows/publish.yaml
@@ -14,8 +14,29 @@
 #   publish:
 #     uses: dart-lang/ecosystem/.github/workflows/publish.yml@main
 
+# Callers may optionally specify the version of the SDK to use when publishing a
+# package. This can be useful if your package has a very recent minimum SDK
+# constraint. This is done via the `sdk` input parameter. Note that this
+# parameter is not required; it defaults to `stable` - using the most recent
+# stable release of the Dart SDK. To pass this value:
+#
+# jobs:
+#   publish:
+#     uses: dart-lang/ecosystem/.github/workflows/publish.yml@main
+#     with:
+#       sdk: beta
+
 on:
   workflow_call:
+    inputs:
+      sdk:
+        description: >-
+          The channel, or a specific version from a channel, to install
+          ('2.19.0','stable', 'beta', 'dev'). Using one of the three channels
+          will give you the latest version published to that channel.
+        default: "stable"
+        required: false
+        type: string
 
 jobs:
   publish:
@@ -29,6 +50,8 @@
     steps:
       - uses: actions/checkout@ac593985615ec2ede58e132d2e21d2b1cbd6127c
       - uses: dart-lang/setup-dart@a57a6c04cf7d4840e88432aad6281d1e125f0d46
+        with:
+          sdk: ${{ inputs.sdk }}
 
       - name: Install firehose
         run: dart pub global activate firehose
diff --git a/pkgs/firehose/CHANGELOG.md b/pkgs/firehose/CHANGELOG.md
index c87b7d1..c17c216 100644
--- a/pkgs/firehose/CHANGELOG.md
+++ b/pkgs/firehose/CHANGELOG.md
@@ -1,3 +1,7 @@
+## 0.3.13
+
+- Added the ability to specify the version of the SDK to use for publishing.
+
 ## 0.3.12
 
 - Don't have issues creating PR comments fail the job.
diff --git a/pkgs/firehose/README.md b/pkgs/firehose/README.md
index 8c5263b..6fcb5e7 100644
--- a/pkgs/firehose/README.md
+++ b/pkgs/firehose/README.md
@@ -77,6 +77,22 @@
     uses: dart-lang/ecosystem/.github/workflows/publish.yaml@main
 ```
 
+## Publishing from a specific version of the SDK
+
+Callers may optionally specify the version of the SDK to use when publishing a
+package. This can be useful if your package has a very recent minimum SDK
+constraint. This is done via the `sdk` input parameter. Note that this parameter
+is not required; it defaults to `stable` - using the most recent stable release
+of the Dart SDK. To pass this value:
+
+```yaml
+jobs:
+  publish:
+    uses: dart-lang/ecosystem/.github/workflows/publish.yml@main
+    with:
+      sdk: beta
+```
+
 ## Workflow docs
 
 The description of the common workflow for repos using this tool can be found at
diff --git a/pkgs/firehose/pubspec.yaml b/pkgs/firehose/pubspec.yaml
index 83a682d..4c0d40b 100644
--- a/pkgs/firehose/pubspec.yaml
+++ b/pkgs/firehose/pubspec.yaml
@@ -1,6 +1,6 @@
 name: firehose
 description: A tool to automate publishing of Pub packages from GitHub actions.
-version: 0.3.12
+version: 0.3.13
 repository: https://github.com/dart-lang/ecosystem/tree/main/pkgs/firehose
 
 environment: