gh-39551: Correct an error message.
    
* src/sage/sat/solvers/dimacs.py: The particle "not" makes all the
difference.

<!-- ^ Please provide a concise and informative title. -->
<!-- ^ Don't put issue numbers in the title, do this in the PR
description below. -->
<!-- ^ For example, instead of "Fixes #12345" use "Introduce new method
to calculate 1 + 2". -->
<!-- v Describe your changes below in detail. -->
<!-- v Why is this change required? What problem does it solve? -->
<!-- v If this PR resolves an open issue, please link to it here. For
example, "Fixes #12345". -->

The patch should be self-explaining. When trying to run a SAT solver
that is not available, I get an error message such as
Could run 'kissat -q /tmp/tmp0r4t8342/tmp_j1161zu3', perhaps you need to
add your SAT solver to $PATH?
Clearly there is a "not" missing.


### 📝 Checklist

<!-- Put an `x` in all the boxes that apply. -->

- [x] The title is concise and informative.
- [x] The description explains in detail what this PR is about.
- [ ] I have linked a relevant issue or discussion.
- [ ] I have created tests covering the changes.
- [ ] I have updated the documentation and checked the documentation
preview.

### ⌛ Dependencies

<!-- List all open PRs that this PR logically depends on. For example,
-->
<!-- - #12345: short description why this is a dependency -->
<!-- - #34567: ... -->
    
URL: #39551
Reported by: AndreasEnge
Reviewer(s): Travis Scrimshaw

Author: Release Manager

src/sage/sat/solvers/dimacs.py

@@ -425,7 +425,7 @@ def _run(self):
         try:
             process = subprocess.Popen(args, stdout=subprocess.PIPE)
         except OSError:
-            raise OSError("Could run '%s', perhaps you need to add your SAT solver to $PATH?" % (" ".join(args)))
+            raise OSError("Could not run '%s', perhaps you need to add your SAT solver to $PATH?" % (" ".join(args)))
 
         try:
             while process.poll() is None: