drop support for gcc-11

Author: ericniebler

.github/workflows/ci.cpu.yml

@@ -24,9 +24,9 @@ jobs:
           - { name: "CPU (clang 16, Debug, TSAN)",   build: "Debug",   tag: llvm16-cuda12.9, cxxstd: "20", cxxflags: "-fsanitize=thread" }
           - { name: "CPU (clang 16, Release)",       build: "Release", tag: llvm16-cuda12.9, cxxstd: "20", cxxflags: "-stdlib=libc++" }
           - { name: "CPU (clang 16, Release, ASAN)", build: "Release", tag: llvm16-cuda12.9, cxxstd: "20", cxxflags: "-stdlib=libc++ -fsanitize=address -fsanitize-ignorelist=/home/coder/stdexec/sanitizer-ignorelist.txt" }
-          - { name: "CPU (gcc 11, Debug)",           build: "Debug",   tag: gcc11-cuda12.9,  cxxstd: "20", cxxflags: "", }
-          - { name: "CPU (gcc 11, Release)",         build: "Release", tag: gcc11-cuda12.9,  cxxstd: "20", cxxflags: "", }
-          - { name: "CPU (gcc 11, Release, ASAN)",   build: "Release", tag: gcc11-cuda12.9,  cxxstd: "20", cxxflags: "-fsanitize=address" }
+          - { name: "CPU (gcc 12, Debug)",           build: "Debug",   tag: gcc12-cuda12.9,  cxxstd: "20", cxxflags: "", }
+          - { name: "CPU (gcc 12, Release)",         build: "Release", tag: gcc12-cuda12.9,  cxxstd: "20", cxxflags: "", }
+          - { name: "CPU (gcc 12, Release, ASAN)",   build: "Release", tag: gcc12-cuda12.9,  cxxstd: "20", cxxflags: "-fsanitize=address" }
           - { name: "CPU (gcc 12, Release, TSAN)",   build: "Release", tag: gcc12-cuda12.9,  cxxstd: "20", cxxflags: "-fsanitize=thread" }
           - { name: "CPU (gcc 13, Debug)",           build: "Debug",   tag: gcc13-cuda12.9,  cxxstd: "20", cxxflags: "", }
           - { name: "CPU (gcc 14, Debug)",           build: "Debug",   tag: gcc14-cuda12.9,  cxxstd: "20", cxxflags: "", }

README.md

@@ -97,7 +97,7 @@ below](#nvhpc-sdk) for more details).
 `stdexec` requires compiling with C++20 (`-std=c++20`) but otherwise does not have any
 dependencies and only requires a sufficiently new compiler:
 
-- gcc 11+
+- gcc 12+
 - clang 16+
 - MSVC 14.43+
 - XCode 16+