ICU-23247 Bump the github-actions group with 2 updates

See #3833

.github/workflows/icu4c.yml

diff --git a/.github/workflows/icu4c.yml b/.github/workflows/icu4c.yml
index f36f1dc..1d89946 100644
--- a/.github/workflows/icu4c.yml
+++ b/.github/workflows/icu4c.yml
@@ -536,7 +536,7 @@
   wasm-wasi-sdk:
     runs-on: ubuntu-22.04  # Updated in BRS
     steps:
-      - uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
 
       - name: Install WASI SDK
         env:

.github/workflows/icu_docs.yml

diff --git a/.github/workflows/icu_docs.yml b/.github/workflows/icu_docs.yml
index e766cfa..16d7961 100644
--- a/.github/workflows/icu_docs.yml
+++ b/.github/workflows/icu_docs.yml
@@ -42,7 +42,7 @@
       - name: Checkout
         uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
       - name: Setup Ruby
-        uses: ruby/setup-ruby@ac793fdd38cc468a4dd57246fa9d0e868aba9085 # v1.270.0
+        uses: ruby/setup-ruby@4c24fa5ec04b2e79eb40571b1cee2a0d2b705771 # v1.278.0
         with:
           ruby-version: '2.7.4' # Not needed with a .ruby-version file
           bundler-cache: true # runs 'bundle install' and caches installed gems automatically

.github/workflows/jekyll-gh-pages.yml

diff --git a/.github/workflows/jekyll-gh-pages.yml b/.github/workflows/jekyll-gh-pages.yml
index 08d5172..1ce0aa7 100644
--- a/.github/workflows/jekyll-gh-pages.yml
+++ b/.github/workflows/jekyll-gh-pages.yml
@@ -39,7 +39,7 @@
       - name: Checkout
         uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
       - name: Setup Ruby
-        uses: ruby/setup-ruby@ac793fdd38cc468a4dd57246fa9d0e868aba9085 # v1.270.0
+        uses: ruby/setup-ruby@4c24fa5ec04b2e79eb40571b1cee2a0d2b705771 # v1.278.0
         with:
           ruby-version: '2.7.4' # Not needed with a .ruby-version file
           bundler-cache: true # runs 'bundle install' and caches installed gems automatically