Fix trivial typos in text

Some are user facing.

Found using

    codespell -q 3 --skip="./Utilities" -I .cmake-whitelist.txt`

whereby the whitelist contained:

    ans
    dum
    helpfull
    emmited
    emmitted
    buil
    iff
    isnt
    nto
    ot
    pathes
    substract
    te
    todays
    upto
    whitespaces

1 files changed, 1 insertions, 1 deletions

diff --git a/Source/cmTimestamp.cxx b/Source/cmTimestamp.cxx
index e747adb..f1e9283 100644
--- a/Source/cmTimestamp.cxx
+++ b/Source/cmTimestamp.cxx
@@ -153,7 +153,7 @@ std::string cmTimestamp::AddTimestampComponent(char flag,
       if (unixEpoch == -1) {
         cmSystemTools::Error(
           "Error generating UNIX epoch in "
-          "STRING(TIMESTAMP ...). Please, file a bug report aginst CMake");
+          "STRING(TIMESTAMP ...). Please, file a bug report against CMake");
         return std::string();
       }