updated to Haskell stack-2.5.1, stackage lts-16.12, ghc-8.8.4;

--- a/Admin/components/components.sha1	Mon Nov 30 16:34:03 2020 +0100
+++ b/Admin/components/components.sha1	Mon Nov 30 17:00:35 2020 +0100
@@ -326,6 +326,7 @@
 fdc415284e031ee3eb2f65828cbc6945736fe995  stack-1.9.1.tar.gz
 6e19948ff4a821e2052fc9b3ddd9ae343f4fcdbb  stack-1.9.3.tar.gz
 f969443705aa8619e93af5b34ea98d15cd7efaf1  stack-2.1.3.tar.gz
+ebd0221d038966aa8bde075f1b0189ff867b02ca  stack-2.5.1.tar.gz
 1f4a2053cc1f34fa36c4d9d2ac906ad4ebc863fd  sumatra_pdf-2.1.1.tar.gz
 601e08d048d8e50b0729429c8928b667d9b6bde9  sumatra_pdf-2.3.2.tar.gz
 14d46c2eb1a34821703da59d543433f581e91df3  sumatra_pdf-2.4.tar.gz

--- a/Admin/components/main	Mon Nov 30 16:34:03 2020 +0100
+++ b/Admin/components/main	Mon Nov 30 17:00:35 2020 +0100
@@ -19,7 +19,7 @@
 spass-3.8ds-2
 sqlite-jdbc-3.32.3.2
 ssh-java-20190323
-stack-2.1.3
+stack-2.5.1
 vampire-4.2.2
 xz-java-1.8
 verit-2020.10-rmx-1

--- a/etc/settings	Mon Nov 30 16:34:03 2020 +0100
+++ b/etc/settings	Mon Nov 30 17:00:35 2020 +0100
@@ -158,9 +158,9 @@
 
 ISABELLE_STACK_ROOT="$USER_HOME/.stack"
 
-ISABELLE_STACK_RESOLVER="lts-13.19"
+ISABELLE_STACK_RESOLVER="lts-16.12"
 
-ISABELLE_GHC_VERSION="ghc-8.6.4"
+ISABELLE_GHC_VERSION="ghc-8.8.4"
 
 
 ###