CI: switch to lua 5.4

current release is 5.4, let's switch to it

.github/workflows/coverity.yml

@@ -22,7 +22,7 @@ jobs:
       run: |
         sudo apt-get update
         sudo apt-get --no-install-recommends -y install \
-          liblua5.3-dev \
+          liblua5.4-dev \
           libsystemd-dev
     - name: Install QUICTLS
       run: |

.github/workflows/vtest.yml

@@ -82,7 +82,7 @@ jobs:
       run: |
         sudo apt-get update
         sudo apt-get --no-install-recommends -y install \
-          liblua5.3-dev \
+          liblua5.4-dev \
           libpcre2-dev \
           libsystemd-dev \
           ninja-build \