ci.yml: upgrade to actions/checkout@v4 and actions/cache@v4

This avoids more warnings from GitHub Actions about a Node.js version
deprecation.

Signed-off-by: Eric Biggers <ebiggers@google.com>
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 66256ed..2e018c3 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -13,56 +13,56 @@
     name: Test building static library
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - run: scripts/run-tests.sh static_linking
 
   dynamic-linking-test:
     name: Test building dynamic library
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - run: scripts/run-tests.sh dynamic_linking
 
   cplusplus-test:
     name: Test using library from C++ program
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - run: scripts/run-tests.sh cplusplus
 
   uninstall-test:
     name: Test uninstalling
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - run: scripts/run-tests.sh uninstall
 
   dash-test:
     name: Test building using the dash shell
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - run: scripts/run-tests.sh dash
 
   license-test:
     name: Test for correct license info
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - run: scripts/run-tests.sh license
 
   gcc-test:
     name: Test with gcc
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - run: scripts/run-tests.sh gcc
 
   clang-test:
     name: Test with clang
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - name: Install dependencies
       run: |
         sudo apt-get update
@@ -73,7 +73,7 @@
     name: Test building 32-bit binaries
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - name: Install dependencies
       run: |
         sudo dpkg --add-architecture i386
@@ -85,7 +85,7 @@
     name: Test with sanitizers enabled
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - name: Install dependencies
       run: |
         sudo apt-get update
@@ -96,7 +96,7 @@
     name: Test with valgrind enabled
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - name: Install dependencies
       run: |
         sudo apt-get update
@@ -107,9 +107,9 @@
     name: Test with BoringSSL
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - name: Cache BoringSSL build
-      uses: actions/cache@v2
+      uses: actions/cache@v4
       with:
         key: boringssl
         path: boringssl
@@ -120,7 +120,7 @@
     name: Test with unsigned/signed char
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - run: scripts/run-tests.sh unsigned_char signed_char
 
   # FIXME: need a Windows build of libcrypto for this to work
@@ -128,7 +128,7 @@
     #name: Windows build tests
     #runs-on: ubuntu-latest
     #steps:
-    #- uses: actions/checkout@v3
+    #- uses: actions/checkout@v4
     #- name: Install dependencies
       #run: |
         #sudo apt-get update
@@ -139,7 +139,7 @@
     name: Run sparse
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - name: Install dependencies
       run: |
         sudo apt-get update
@@ -150,7 +150,7 @@
     name: Run clang static analyzer
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - name: Install dependencies
       run: |
         sudo apt-get update
@@ -161,7 +161,7 @@
     name: Run shellcheck
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - name: Install dependencies
       run: |
         sudo apt-get update