fix: global installs do not work as I expected (#319)

.github/actions/slackify-markdown/action.yml

@@ -19,12 +19,21 @@ runs:
       uses: actions/setup-node@v3
       with:
         node-version: 16
+    - name: Create and initialize slackify directory
+      shell: bash
+      run: | # We need to create a directory to install the slackify-markdown package to avoid conflicting with repositories using pnpm.
+        mkdir slackify
+        cd slackify
+        npm init -y
     - name: Install slackify-markdown package
       shell: bash
-      run: npm install -g [email protected]
+      working-directory: slackify
+      run: |
+        npm install [email protected]
     - name: Slackify
       uses: actions/github-script@v6
       id: slackify
+      working-directory: slackify
       env:
         MARKDOWN: ${{ inputs.markdown }}
       with:
@@ -37,4 +46,8 @@ runs:
               core.setOutput('text', mrkdwn);
           } catch (error) {
               core.setFailed(error.message);
-          }
+          }
+    - name: Clean up slackify directory
+      shell: bash
+      run: |
+        rm -rf slackify