Added pullRequestNumber to the action's outputs (#167)

* feat: set pullRequesstNumber as action output

* chore: add changeset

* fix: feedback from pr review

* Update .changeset/long-mayflies-yell.md

Co-authored-by: Mateusz Burzyński <mateuszburzynski@gmail.com>

Co-authored-by: Mateusz Burzyński <mateuszburzynski@gmail.com>

src/run.test.ts

@@ -57,6 +57,10 @@ describe("version", () => {
       () => ({ data: { items: [] } })
     );
 
+    mockedGithubMethods.pulls.create.mockImplementationOnce(
+      () => ({ data: { number: 123 } })
+    );
+
     await writeChangesets(
       [
         {
@@ -92,6 +96,10 @@ describe("version", () => {
       () => ({ data: { items: [] } })
     );
 
+    mockedGithubMethods.pulls.create.mockImplementationOnce(
+      () => ({ data: { number: 123 } })
+    );
+
     await writeChangesets(
       [
         {
@@ -123,6 +131,10 @@ describe("version", () => {
       () => ({ data: { items: [] } })
     );
 
+    mockedGithubMethods.pulls.create.mockImplementationOnce(
+      () => ({ data: { number: 123 } })
+    );
+
     await writeChangesets(
       [
         {