github: Evict old entries from ccache

We don't want to build old versions using these caches, so we don't
need old entries (if header files change, there could be lots of
differences that increase the cache size unnecessarily).

.github/workflows/tkm.yml

@@ -15,6 +15,7 @@ env:
   CCACHE_COMPILERCHECK: content
   CCACHE_COMPRESS: true
   CCACHE_MAXSIZE: 100M
+  EVICT_CCACHE_AGE: 1200s
 
 jobs:
   pre-check:
@@ -52,6 +53,7 @@ jobs:
             -e CCACHE_COMPILERCHECK \
             -e CCACHE_COMPRESS \
             -e CCACHE_MAXSIZE \
+            -e EVICT_CCACHE_AGE \
             strongswan-tkm \
             bash -c "ccache -z; \
             echo '### build charon-tkm'; \
@@ -75,6 +77,8 @@ jobs:
             make -j check TESTS_RUNNERS=tkm TESTS_TKM=1 || exit 1; \
             cat /tmp/tkm.log; \
             ccache -sv; \
+            ccache --evict-older-than $EVICT_CCACHE_AGE; \
+            ccache -sv; \
             "
       # delete old cache entry as we currently can't update it any other way
       - env: